Mr. A, Adams on the Animals of certain Mollusca. 111 
are as long as the tentacles, and flattened; and the eyes are not 
well developed—less so on the right side than on the left, The 
absence of a rostrum, and other peculiarities, perfectly justified 
the learned Doctor in raising Umbonium to the rank of a family. 
Mr. Fairbank had evidently seen the animal alive ; but, owing to 
his imperfect acquaintance with the nature or names of the 
organs of Mollusca, his description is not only obscure, but 
absurd. 
Genus Puorinuta, H. & A. Adams. 
In the animal of the species of Photinula, which I observed, 
the eye-pedicels are not so distinct from the tentacles as in most 
Trochide ; the head-lobes are simple, the muzzle is broad, the 
neck-lappets are large, and there are four tentacular filaments 
on each side on the lower edge of the lateral membrane. From 
this description it will be seen that the position assigned to this 
genus by Dr. Gray, in his ‘Guide to Mollusca,’ is not correct, 
the animal differing very materially from that of the genera Um- 
bonium or Rotella. It indeed belongs to the Trochide, and is 
most nearly allied to Margarita; but the shell differs in texture 
and form, and is not umbilicated. In Gibdula the number of 
the lateral vibracula is three on each side; the same appears to 
be the case in Oxysitele, which genus Photinula most resembles ; 
while in Margarita there are five filaments on each side—two 
on the lateral membrane, and three on the opercular lobe. 
Genus Macroscuisma, Swainson. 
At Tabu-Sima, a small island about thirty miles from Niegata, 
in Niphon, Japan, I dredged, at 25 fathoms, and at a quarter of 
a mile from the shore, two living examples of Macrosehisma. 
The shell is not situated near the hinder end of the animal 
(as Mr. Cuming, to the best of his recollection, believes), but on 
the fore part; and the apex of the shell is not anterior, as Dr. 
Gray states, but subcentral and inclined backwards. 
The animal is very large and elongated, bearing the shell in 
a sloping direction obliquely upwards on the fore part of the 
body. ‘he tentacles are filiform and very long, with the eyes 
large, black, and conspicuous, on slight swellings at their outer 
bases. ‘The front edge of the mantle is extended, and gives the 
appearance of a large veil over the head, The manile is not 
developed, covering the shell, as in /issurellide ; and neither the 
mantle-margin nor anal tube is fringed. The edge of the 
mantle is furnished with short papille, four on each side and 
two behind, which are recurved over the edge of the shell. The 
anal tube is elongate and cylindrical, and is directed backwards 
and a little upwards through the fissure in the shell. The foot, 
