Mr. A. Adams on the Animals of certain Mollusca. Ill 



arc 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 Photinula, 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 

 Trochidse ; 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 Urn,' 

 Ionium or Rotella. It indeed belongs to the Trochidse, and is 

 most nearly allied to Margarita ; but the shell differs in texture 

 and form, and is not umbilicated. In Gibbula the number of 

 the lateral vibracula is three on each side ; the same appears to 

 be the case in Occystele, 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 Macroschisma, 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 Macroschisma. 



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. The tentacles are filiform and very long, with the eye3 

 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 mantle is not 

 developed, covering the shell, as in Fissurellidce ; and neither the 

 mantle-margin nor anal tube is fringed. The edge of the 

 mantle is furnished with short papillse, 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, 



