THE GEOLOGICAL MAGAZINE. No. LX-JUNE, 1869. ORIGINAL ARTICLES. I.-GEMS FROM PRIVATE COLLECTIONS, No. 1. ON EUCLADIA, A NEW GENUS OF OPHIURIDE, FROM THE UPPER SILURIAN, Dudley. BY HENRY WOODWARD, F.G.S., F.Z.S., etc., of the Geological Department, British Museum. THE (PLATE VIII.) HE beautiful fossil Star-fish, which forms the subject of this paper, and is represented of the natural size upon the accompanying Plate VIII., is from the cabinet of Mr. Henry Johnson, of Dudley, the Honorary Secretary of the South Staffordshire and East Worcestershire Institute of Mining Engineers. It was obtained some years since in the shale between the Wenlock and Aymestry Limestones (probably Lower Ludlow shale), at Sedgley, near Dudley. The specimen exhibits the ventral surface of the body of the animal, surrounded by five bifurcating arms, each furnished with five pairs of stout pinnæ, the first pair springing from near the commencement of the arm and being inserted close to the border of the petal-shaped pentagonal (oral) plate (Plate VIII., Fig. 1 a., c.) ; each pair of pinnæ increasing in size in proportion as it recedes from the central disk, the pair nearest the mouth being the smallest. The arms and pinnæ are nearly round in section, and taper gently towards their extremities; the surface of both is everywhere covered with minute imbricated plates, the projecting points of which give it an extremely scabrous appearance (See Fig. 1a and 1d). On carefully removing a portion of one of the arms at the part marked z, the same rugose surface was exposed; the arm at this point had been compressed, apparently before it had become mineraiized; other arms, as those for instance at the point w, displaying, where broken off, a nearly round section. The pinna, which diverge obliquely outwards on either side from the point of their attachment to the arms, curve downwards at their extremities and are lost in the matrix upon which the specimen rests, nor can the arms themselves be traced quite to their extremities, the points being either buried in the matrix or broken off. One arm, originally springing from the point marked x, is only indicated by a 1 From ev beautiful, κλádos branch. VOL. VI.-NO. LX. εν 16 fragment of its base and one of its first pair of pinna. On carefully examining the sides of the arms, where exposed, a few bases of broken off spines can be detected, indicating probably that the arms were originally spinous along their borders. At the point m, Fig. 1 a., the madreporiform tubercle can be distinctly seen in situ, occupying the same relative position in the fossil which it does in all the living species of Ophiuride. The centre of the body of the animal is marked by a rosette composed of five pairs of plates, forming a pentagonal figure, each pair being anchy losed together, and forming at the outer margin a rounded lobe-like the petal of a flower. Between each of these is inserted the base of one of the five arms articulated and united to the pentagonal plates by a pair of styliform processes given off from the external margin of each lobe (see s, Fig. 1 a). The body appears to have been discoidal, and was probably of considerable thickness, but the hard stony matrix precludes the possibility of ascertaining its extent. We are able, nevertheless, to perceive between the arms several of the pentagonal and hexagonal plates, which formed the covering of the disk, still in situ (see d, d, d, Fig. 1 a, and Fig. 1 c), the surface of which is covered with minute tubercles, several of which near the madreporiform body are elevated into prominent papillæ (see p, Fig. 1b). From the position of the madreporiform tubercle (m) with regard to the central pentagonal plates (c, Fig. 1a), there is no reason to doubt that these are the true oral plates, and as additional evidence, it will be observed that the arms take their origin from the margin of the pentagonal rosette, and overlie the body-disk, as in all the living Ophiuridae; the pinnæ also take their origin from the same surface of the arms; the pinnæ in the Echinodermata being invariably placed on the innermost border of the arms near the mouth. After a careful examination of the bibliography of the class Echinodermata, and a comparison of the fossil under consideration with all those forms of recent and fossil star-fishes likely to aid me in my investigation, I have been led to refer it to the order Ophiurida. The members of this group are very distinct from the true star-fishes (Asteriada) on the one hand, and the Crinoidea on the other. 1 "In fact," writes Prof. Edward Forbes, "they hold the same relation to the Crinoidea that the true star-fishes hold to the sea-urchins" (Echinidae). "They are Spinigrade animals, and have no true suckers by which to walk, their progression being effected (and with great facility) by means of five long flexible-jointed processes, placed at regular distances round their body, and furnished with spines on the sides and membranous tentacula. These processes are very different from the arms of the true star-fishes, which are lobes of the animal's body; whereas the arms of the Ophiurida are superadded to the body, and there is no excavation in them for any prolongation of the digestive organs." Of the families Ophiura and Euryales, included in this order, 1 66 History of British Star-fishes," p. 19. the former have simple arms, whilst those of the latter ramify into many processes. Although the fossil under consideration most nearly approaches Euryalus, it cannot be, with propriety, referred to that or any known genus of Ophiurida, recent or fossil. In Euryalus the five arms branch dichotomously from their roots with cirrhous extremities, but they are not furnished with pinnæ. The interbrachial spaces in the body-disk of Euryalus are membranous, whilst in the fossil, as we have seen, they are protected with a covering of calcareous plates more nearly resembling, in this respect, the body-disk of Ophiura. The addition of pinnæ to the arms, together with their bifurcated character offers an analogy to the Crinoidea, thus aiding us in filling up another gap in the chain by which the forms that existed in Palæozoic times are linked to those of our own. We have in this fossil presented to us a type of Palæozoic starfishes extending its affinities towards the Comatula on the one hand and to Ophiura and Euryalus on the other; exemplifying what Professor Owen has so happily termed "a more generalized type of structure" than any at present existing in the class Echinodermata. The same writer observes :-"As we advance in our survey of the organisation and metamorphoses of animals, we shall meet with many examples in which the embryonic forms and conditions of structure of existing species have, at former periods, been persistent and common, and represented by mature and procreative species." Having been informed that at a meeting of the Dudley and Midland Geological and Scientific Society (held some years since) Mr. J. W. Salter suggested that this specimen should be named Eucladia Johnsoni, I have great pleasure in carrying his suggestion into effect. The star-fish rests upon a slab covered with numerous small Brachiopods (Rhynchonella borealis?), fragments of Trilobites, Crinoids, etc., presenting the appearance of having been quietly washed on shore, mouth uppermost, and being unable to right itself, it had been left to die, and finally to become imbedded in the superimposed sediments, a fossil of rare beauty, and a happy "find" for the Dudley collector. Dimensions of Eucladia Johnsoni :-Diameter of pentagonal plates, eight lines; diameter of disk, two inches; diameter of madreporiform body, two lines; greatest length of arm preserved, 2 inches. From centre of disk to bifurcation of arms, 1 inches. [It was with no small satisfaction that, in turning over some MSS. of my late brother, Dr. S. P. Woodward, I met with an admirable photograph of this fossil (taken in 1863, by the late L. P. Capewell, Esq., of Dudley), bearing the following memorandum in his own hand-writing:"Euryalus? Wenlock Limestone, Dudley (Mr. Henry Johnson, Mining Engineer, Dudley). Arms five, about five inches long, covered with strong tubercles, central plates, five pairs, madreporiform tubercle. Photographed by Mr. Capewell."] 66 1 Lecture X. Echinoderma, p. 129. Invertebrata." By Prof. Owen. 1843. Comparative Anatomy and Physiology of the The following is a list of the known genera and species of fossil star-fishes (Asteriada and Ophiurida), from the Silurian rocks, with a reference to their authorities, formation, and locality : I. II. Edrioaster Bigsbyi, Billings, Trenton L. Ottawa City, Canada West. III. 1. Glyptaster brachiatus, Hall, Silurian (several stages), New York. IV. V. 2. 3. pentangularis, Hall, Lepidaster Grayi, Forbes, Memoirs Geol. Surv., Dec. 3. 1850. U. Silurian, Dudley. 1. Palæaster asperrima, Salter, 1857. Ann. and Mag. Nat. Hist. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 2nd series, Vol. xx. p. 325, pl. ix. fig. 1. Caradoc, or Bala Sandstones, near Welchpool, N. Wales. (Uraster) obtusa, Forbes. Mem. Geol. Surv., 1849. Decade 1, pl. i, fig. 3. Caradoc, Drumcannon Waterford Bala Rocks, Moel-y-Garnedd. coronella. Salter, 1857. Ann. and Mag. Nat. Hist. op. cit. p. 326. May Hill Sandstone. Malvern, (Uraster) Ruthveni, Forbes, 1849, op. cit. Decade 1, pl. i. fig. 1. hirudo, Forbes, 1849, loc. cit. pl. i. fig. 4. Ludlow Rocks, Niagarensis, Hall, Paleontology of New York, Trenton Limestone. New York. (Asterias) matutina, Hall, Paleontology, New York. Vol. i. p. 91, pl. xxix. fig. 5. Twentieth Report of State Cabinet, Palæaster Shafferi, Hall; 20th Report, 1866, p. 4, pl. ix. fig. 1. granulosa, Hall; 20th Report, 1866, p. 5. Same formation as last (Asterias) antiquata, Locke, Proceeds. Acad. Nat. Soc., Philadel- Hall, 20th Report on State Cabinet, 1866, p. 7. Hudson's River Group, Harpeth River, Davidson County, Tennesse. eucharis, Hall, 20th Report, 1866, p. 7, pl. ix. fig. 3. Hamilton Group, Hamilton, Madison Co., etc., etc. constellata, Thorent, Lower Green Schists, Lower Silurian, Mondrepuis, Aisné, France. imbricata, Salter, n. sp. Caradoc. Llanfyllin, Montgomeryshire, parviuscula, Billings, Clinton Group, Arisaig, Nova Scotia. VI. 1. Palasterina antiqua, Hisinger, Lethæa Suecia, p. 89, t. 26, fig. 6. Ludlow (Uraster) primava, Forbes, 1849, op. cit. pl. 1, fig. 2. stellata, Billings, Geol. Surv., Canada. Org. Rem. Decade iii. rigida, Billings, Trenton Limestone, Ottawa City, Canada West. VII, 1. Palaocoma Marstoni, Salter, 1857, op. cit. p. 328, pl. ix. fig. 3. Ludlow, Church Hill, Leintwardine, Lower |