the circulation in the kidney of dog-fish and rabbit.

11. Give an account of the cranio-facial apparatus of the dog-fish.
State clearly what representation of this occurs in the frog and in the
rabbit.

12. Give drawing (a) from above, (b) from the side, of the dog-fish
brain.

13. State the origin and the distribution of the fifth, seventh, ninth, and
tenth cranial nerves in the dog-fish.

14. Compare, one by one, the cranial nerves of the dog-fish with those
of any higher vertebrate, as regards their origin and their distribution.

15. Describe the auditory organ of the dog-fish. What parts are added
to this in the higher type?

16. Draw the cloaca (a) of a male, (b) a female dog-fish.

17. (Practical.) Demonstrate in a dog-fish the pathetic nerve, the
opening between pericardium and coelom. the abdominal pores, and
the ureter.

-Amphioxus_

1. _Anatomy_

Section 1. We find in Amphioxus the essential vertebrate features
reduced to their simplest expression and, in addition, somewhat
distorted. There are wide differences from that vertebrate plan with
which the reader may now be considered familiar. There are no
limbs. There is an unbroken fin along the median dorsal line and
coming round along the ventral middle line for about half the animal's
length. But two lowly vertebrates, the hag-fish and lamprey, have no
limbs and a continuous fin. There is, as we shall see more clearly, a
structure, the respiratory atrium, not apparently represented in the
true vertebrate types, at least in their adult stages. There is no
distinct heart, only a debateable brain, quite without the typical
division into three primary vesicles, no skull, no structures whatever of
cartilage or bone, no genital ducts, no kidneys at all resembling those
of the vertebrata, no pancreas, no spleen; apparently no sympathetic
chain, no paired sense organs, eyes, ears, or nasal sacs, in all of
which points we have striking differences from all true vertebrata; and
such a characteristic vertebrate peculiarity as the pineal gland we can
only say is represented very doubtfully by the eye spot.

Section 2. The vertebral column is devoid of vertebrae; it is
throughout life a rod of gelatinous tissue, the notochord (Figure 1,
n.c.), surrounded by a cellular sheath. Such a rod is precursor to the
vertebral column in the true vertebrates, but, except in such lowly
forms as the lamprey, is usually replaced, partially (e.g., dog-fish)
or who