7. Cysticercus taniæ flavopunctata, also at

present unknown.

(b.) Echinococci. 8. Echinococcus hominis (RUDOLPHI), the larva of Tania echinococcus.

II. TREMATODA-Fluke-like parasites.

1. Fasciola hepatica (LINNEUS); vel, Distoma hepaticum (RUDOLPHI).

2. Distoma crassum (BUSK); vel, Distoma Buskii (LAN

KESTER).

3. Distoma lanceolatum (MEHLIS).

4. Distoma ophthalmobium (DIESING).

5. Distoma heterophyes (SIEBOLD).

6. Bilharzia hæmatobia (COBBOLD); vel, Gynæcophorus
hæmatobius (DIESING).

7. Tetrastoma renale (DELLA Chiaje).
8. Hexathyridium pinguicola (TREUTLER).

9. Hexathyridium venarum (TREUTLER).

B. HOLLOW WORMS-NEMATELMIA; vel, CŒLELMINTHA.

I. ASCARIDES-Unisexual, body attenuated posteriorly, and still more so anteriorly, mouth with three tubercles, tail of the male narrower than that of the female.

1. Ascaris lumbricoides (LINNÆUS).

2. Ascaris mystax (RUDOLPHI, COBBOLD); vel, Ascaris alata (BELLINGHAM).

3. Trichocephalus dispar (RUDOLPHI).

II. OXYURIDES-Unisexual, body more attenuated posteriorly than anteriorly, rudimentary tubercles round the mouth, tail of male thickened.

1. Oxyuris vermicularis (BREMSER).

III. TRICHINE-Unisexual, cystic, and free.

1. Trichina spiralis (OWEN).

IV. SCLEROSTOMA-Unisexual, body slightly attenuated anteriorly, mouth with four hooks, tail of male cup-shaped.

1. Sclerostoma duodenale (COBBOLD); vel, Ancylostoma duodenale (SIEBOLD).

V. STRONGYLUS-Unisexual, body attenuated posteriorly, mouth with six lobes, tail of male cup-shaped.

1. Strongylus bronchialis (COBBOLD); vel, Filaria bronchialis (RUDOLPHI).

2. Eustrongylus gigas (DIESING); vel, Strongylus renalis (MOQUIN-TANDON).

VI. SPEROPTERA-Unisexual, tail spiral, and furnished with marginal appendices.

1. Speroptera hominis (RUDOLPHI).

VII. FILARIA-Unisexual, body equal (filiform), mouth with three tubercles, tail simple.

1. Filaria lentis (DIESING); vel, Filaria oculi humani (NORDMANN).

2. Filaria medinensis (GMELIN).

C. A third class may provisionally be regarded as accidental
Parasites. These are-

Pentastoma constrictum (lung, liver; W. Coast of Africa).
Anthomia caricularis, larva, exciting causes of boils.

Pentastoma denticulatum vestris hominis (SIEBOLD), liver and
small intestines."

*By some Naturalists the Demodox is ranked among the Acaridæ, by

others among the Rotiferæ.

Alternation of generation, or Metagenesis, first described by Steenstrup, is well exemplified in the development of the tænia solium, or common tape-worm. This worm, when mature, inhabits the intestines of the human subject. It consists of a minute head, terminating in a convexity, surrounded with a double row of hooks; posterior to this convexity there are situated four equi-distant cups or suckers. The head is followed by a slender neck that presents transverse markings, and to this succeeds the body, which consists of a number of similar segments, termed Zoonites, or Proglottides. Each segment is hermaphrodite, contains numbers of ova, and is expelled in this state per rectum. Every mature ovum is protected by a leathery capsule, which ensures its vitality for a long time after the segment has disappeared by putrefaction. The majority of these ova perish, but some are swallowed by other animals; and when one of these ova is swallowed by the pig an embryo is set free, termed a proscolex, provided with three pair of spikelets, by means of which it makes its way to some resting place, or perchance it may enter a mesenteric vein, and be carried by the blood to the liver; in either case it becomes encysted and constitutes a cysticereus, or echinococcus, the embryo per se being called a scolex. In this condition some transverse lines may make their appearance on its neck, indicative of future segmentation, when it is technically termed a strobila embryo. It never reaches any further stage of development, unless it is swallowed by man, when it becomes developed into the perfect tænia solium. Accordingly, it passes through the following stages, viz. :—ovum, proscolex, scolex, strobila embryo, and tænia solium. Man generally becomes infested with the tape-worm from eating diseased pork, for these worms constitute the disease called measles in the pig.

REPRODUCTION.

I have here copied from Dr. Mapother's work on Physiology a tabulated arrangement of the several methods of reproduction, framed by Professor A. Thomson, to which Dr. Mapother has added an example of each.

K

NON-SEXUAL.

“FISSIPAROUS—Parent splits, each part a new animal.

1. Transverse-Amœba.

2. Longitudinal-Vorticella.

3. Irregular-Gonium.

Parent splits and discharges the young-Volvox.

"GEMMIPAROUS-Budding upon the parent stock-Hydra.
Separated buds. Gemmæ or sporules.

1. On all parts of the body-Medusa.
2. On one part or organ only-Tunicata.

SEXUAL.

"HERMAPHRODITE-Both sexual organs on one individual. 1. Self-impregnation-Tape-worm.

2. Mutual impregnation-Snail.

“DIÆCIOUS--Oviparous, laying eggs which are hatched. 1. External fecundation-Herring.

2. Internal fecundation-Fowl.

Ovo-viviparous. Eggs hatched within the maternal body-Snake.

Mammiferous, suckling the young.

1. Monotrematous-Ornithorynchus.

2. Marsupial-Kangaroo.

3. Placental, or strictly viviparous-Man."

EXAMPLES

OF THE KIND OF QUESTIONS ON

ZOOLOGY AND COMPARATIVE ANATOMY,

GIVEN BY SOME OF THE

PRINCIPAL EXAMINING BOARDS

IN ENGLAND AND IRELAND.

LONDON UNIVERSITY.

Give an account of the structure of the human eye-ball: compare the structure of the eye with that of the ear; and state what are the principal modifications undergone by the organ of vision in the Animal Kingdom.

What is the meaning of the term "Homology?" On what grounds is it justifiable to assert that two organs or parts are homologous ? Illustrate your

answer by examples.

What are the chief anatomical and physiological peculiarities of the Cephalopoda ?

Enumerate the most important distinctive characters of the skeletons of an Amphioxus, a lamprey, a cod-fish, and a shark.