"sented in Plates XXV. figs. 1, 2, 3. and XXVI. "fig. 7. of the volume above referred to. This tube is "continued through the whole length of the siphon, "and from its present irregular shape appears to have "been composed of a coriaceous substance, capable of "dilatation and contraction. The space within the si"phon, between its interior walls and the outside of "the included tube, has a number of plates radiating "from the latter, throughout its entire length, and "apparently connecting it with the inner walls of the siphon; but these plates are too much covered by "sparry crystallisation to enable us clearly to make out "their character. This tube may have been the organ "into which water could be received, when the animal 66 required an increase of its specific gravity in order to "descend; a purpose which is supposed to be served "by the siphon of the nautilus and other chambered "shells. "There is also one specimen, which, though not in good preservation, is doubtless a Catenipora or chain "coral, a genus characteristic of the older transition "limestones, in which beds also, orthocerata are "common." General List of Specimens, brought to England by Captain Back.* FROM THE ATHABASCA (or Elk) RIVER; (probably from one of the Portages).- Porphyritic, grey, compact felspar, enclosing grains of quartz, and of crystalline felspar. These specimens have been compared with those in Dr. Richardson's collection, now in the museum of the Geological Society, of which a list is given in the Geological Appendix to Franklin's Second Journey. The numbers of the corresponding specimens in that list are indicated below. Cream-coloured limestone, effervescing slowly, containing impressions of shells, and occasional nests of crystallised magnesian carbonate of lime, and in some places stained with bitumen *: found in horizontal strata on the bank of the river. This rock much resembles some of the specimens from the "Ramparts" on the Mackenzie River - Dr. Richardson's list, Nos. 148-156. p. xxxiv. xxxv.; and from Lake Winnipeg, No. 1014. p. liv. - GREAT SLAVE LAKE. Hard slaty limestone, effervescing very slowly. "From an island of large extent in horizontal strata." Compare with Richardson's, Nos. 60. 132. p. xxxi.; 205. p. xliv.; 246. 293. p. vi. From CHRISTIE'S BAY (Peth-the-nu-eh). Slaty (magnesian) limestone, with a vein of sparry magnesian carbonate of lime. Compare with Dr. Richardson's, No. 228. p. v. from the mouth of Dease's River, head of Great Bear Lake; and 208. p. xiv. from Cape Parry. From a small bay in GAH-HOOA-TCHELLA. A specimen, which formed part of a boulder, found loose on the beach by Mr. King the surgeon of the expedition, consists of limestone, effervescing copiously, and exhibiting on the decomposed surface concretional grains like some varieties of oolite; and containing also portions of a fossil, the external structure of which resembles the genus Stromatopora of Goldfuss. Among the specimens which have an organised structure, probably from the shores of this lake, is one with a tuberculated surface, composed of calcareous matter, which Mr. Lonsdale considers as belonging to the genus Stromatopora of Goldfuss, and probably to his species polymorpha (Plate LXIV. fig. 8. d.) This occurrence of bituminous matter in limestone, nearly bordering on a large tract of crystalline and igneous rocks, may deserve attention with reference to the hypothesis of Dolomization; which regards the introduction, or development, of magnesia as subsequent to the deposition of the calcareous matter, and as connected with the proximity of masses containing that earth, and heated to a very high temperature. From FORT RELIANCE, at the Eastern Extremity of Great Slave Lake. - Granite of several varieties. Some specimens having the aspect of sienite; others containing flesh-red felspar, in large crystals,-described as "forming undulating rocks of considerable altitude." Some specimens from this quarter approach to gneiss; having a foliated structure, with mica in very large proportion. From the beach, at the entrance of the Lake, is a siliceous conglomerate; consisting of worn pebbles of flint, cemented by a paste composed of sand and calcareous (effervescent) matter. The following were found in the form of loose worn pebbles, on the shore of the lake, near Fort Reliance : — Bluish grey strip chalcedony; quartz crystals; quartz of various shades of grey and brown; flinty slate; brown jasper; with fragments of a conglomerate, consisting of portions of reddish jasper, in a dark grey paste. From HAWK RAPIDS.-(Lat. 66° 33°, Long. 102° 40′)— Reddish granite; some specimens indicating a slaty structure. Grey quartz, apparently a portion of a vein. From ROCK RAPID. — (Lat, 65° 50′, Long. 98° 20′) — Granite of different shades of reddish and grey. From POINT BACKHOUSE, in the estuary of Back's River. -Reddish granite of moderately fine grain. And lastly,- From a " Bluff, NORTH OF POINT BeauFORT." Bluish grey granite of fine grain. No. V. METEREOLOGICAL TABLE, ARRANGED FROM THE REGISTERS KEPT AT FORT RELIANCE BY CAPTAIN BACK AND MR. KING. THE following table exhibits the temperature of the air and principal atmospherical phenomena observed at Fort Reliance, from the commencement of November, 1833, to the end of May, 1834; and from the 22d of October, 1834, to the 18th of March, 1835. The temperatures were registered fifteen times in the twenty-four hours, between six o'clock in the morning and midnight. The daily means were obtained from the fifteen observations. The four thermometers which were used were coloured spirit ones, made by Newman, and were hung up on the north side of the observatory where they were registered; but finding that they varied from each other as the temperature decreased, and that one gave nearly the mean of the whole, it was afterwards used as the standard thermometer, and from it the observations were made. The remarks made on preceding voyages regarding the generally calm state of the atmosphere during intense cold are in a great measure corroborated by the following table, though in some few instances it will be seen that a very low degree of the thermometer was accompanied by a breeze preceding or immediately following a calm. |