640 The American Naturalist. [July. 
Twelve delicate tentacles project from the mouth into the pharynx. 
The atriopore seems to coincide with the thirty-sixth myotome, the 
anus with the fifty-first. The formula would, therefore, be 36-15-10-= 
61. The number of dorsal fin rays is 250-260, although there are 
none over the last six myotomes ; there are thus about five to a myo. 
tome ; but there does not seem to be any fixed relation between the 
two numbers, especially as the ventral fin rays are proportionately less 
numerous, — thirty-four or rather more in twelve myotomes. The finrays 
lie in a compartmented lymph-space, which is antecedent to the rays and 
extends beyond them, both fore and aft. The coelomic sacs, in which 
the reproductive cells develop, correspond to twenty-six myotomes. The 
pre-oral tentacles vary in number, but are always fewer in young ex- 
amples. They are formed in pairs. After the larval phase is passed 
all relation is lost between the number of myotomes and that of the 
gill-slits, which latter numbered ninety-six in specimens a little under 
an inch in length, and one hundred and twenty-four in larger exam- 
ples. Each primary gill-slit is borne upon a solid chitinous rod, and 
each becomes secondarily divided by the growth of a tongue in the di- 
rection of the length of the slit : these tongues are carried upon hollow 
chitinous rods. 
The body contains three kinds of spaces, which are filled with 
lymph: (i) the atrial chamber, (2) the enteric spaces, (3)the hsemo- 
lymph cavities. An atrial cercum extends back to beyond the atrio- 
pore. The enteric cavity consists of atrium, intestine, and caecum, 
the last given off as a diverticulum at the 28th or 29th myotome, and 
reaching forward to the 14th or 15th in adults. The vascular system 
seems to be in a state of degeneration. Certain of the vascular 
trunks are continuous with the lymph spaces, so that the vascular and 
lymphatic systems cannot be distinguished. The metapleural lymph 
canals disappear when the gonads are ripe, and it does not appear 
improbable that their lymph serves as a final supply of nutriment to 
the gonads. 
Dr. Lankester has discovered two short, wide, brown funnels oppo- 
site to the 27th myotone ; the wide end turned toward the atrium, the 
narrow directed to the dorso-pharyngeal coelom, and thus serving to 
place the latter in communication with the former. Dr. Lankester's 
memoir is illustrated with five plates. 
Note on Ammocoetes Branchialis (Linnaeus).— Previous 
to the fall of 1885 we had no positive record of this species from 
localities other than from Central and Southern Indiana, and from 
Southern Wisconsin. On May 8, 1886, Professor S. A. Gage and 
