REPORT O N THE PTEROPODA. 
47 
gives origin to one, whilst three nerves spring from the left ganglion, which are 
distributed in a manner precisely similar to the corresponding nerves in the 
Pneumonodermatidae. The nerve from the right ganglion innervates the right 
side of the visceral sac, one of its branches subdivides to supply the osphradium, 
which has the form of a ciliated nervous band, situated in the antero-lateral 
angle of the cloacal depression (PL IY. fig. 10). 
There is no difference between the stomato-gastric nervous system of 
Clionopsis and that of the Pneumonodermatidae. 
Family III. C l i o n i d je. 
The Head of the Clionidse differs from that of the Pneumonodermatidae and 
the Clionopsidae in its anterior extremity, which is swollen and separated from the 
body by a “neck. - ’ The anterior tentacles are long, and have the same structure as 
those of the Pneumonodermatidae. The posterior are situated on the margin of the 
distended portion of the head towards the neck, and are shaped as in the two preceding 
families. 
The buccal aperture is capable of opening widely, and its margins separate when the 
anterior portion of the digestive tract is evaginated (PI. Y. fig. 4). When the evaginable 
parts are retracted, the margins of the buccal opening close upon each other like two 
half hoods over the buccal cavity. 1 
The Foot is shaped almost exactly as in the Pneumonodermatidae, but does not 
exhibit the plicated tubercle at the base of the posterior lobe. The visceral sac has no 
dorsal glandular patch as in the preceding families. 
The Digestive Tract . — The anterior evaginable portion or proboscis is much shorter 
than in the Gymnosomata already examined (see PI. V. fig. 4, a). At the base of this 
evaginable proboscis are conical buccal appendages (to the number of two or three pairs, 
symmetrically disposed on either side), and known as buccal cones or cephaloconi (PI. Y. 
fig. 4, c). I have already 2 described their structure, and now limit myself to mentioning 
the points which were then demonstrated : — 
1. That they do not bear suckers of any kind. 
2. That they present special nervous terminations, and enclose in their interior long 
unicellular glands collected into follicles. 
I must add, however, that my sections were made from contracted cones from 
specimens killed in alcohol, so that the groups of columnar epithelial cells surrounding 
1 See Pelseneer, The cephalic appendages of the Gymnosomatous Pteropoda, Quart. Journ. Micr. Sci., 1885, 
vol. xxv. pi. xxxv. figs. 4, 2. 
5 Ibid., pp. 495-500, pi. xxxv. figs. 11-22. 
