NATURAL SCIENCES OF PHILADELPHIA. 171 
Zonites and Hyalina, respectively characterized by the presence or 
absence of a distinct locomotive disk to the foot, 
and well-marked furrows running above, and 
parallel to, the edge of the foot, meeting above 
‘ the extremity of the tail over a distinct caudal 
Tail of Zonites mucous pore (fig. 15). I now place them all in 
Bier ati Zonites, as all I have examined are so charac- 
terized, and I believe all will prove to be so. (See Ann. N. Y. 
yes N. Hi, X. 164.)' 
' The external orifice of the generative organs in the species I 
have examined is quite under the mantle, not on the right side of 
the head, as inadvertently stated on p. 29 of L. and Frw. Shells, I. 
Genus VITRINA, Drap. 
To the description of the animal on p. 29 of L. and Frw. Sh. N. 
A., I., must be added the fact of there being a distinct locomotive 
disk to the foot. 
Lingual dentition of V. limpida. [Morse.] 
The jaw is highly arched, ends acuminated, blunt; anterior sur- 
face smooth; cutting margin with a prominent beak-like median 
projection. I have figured the jaw of V. lampida on pl. XVI., fig. 
3. I have found it to be the same in V. exilis and Pfeiffert. I 
have not examined either jaw or lingual membrane in V. Angelice. 
Fig. 16 gives a general idea of the lingual membrane. The cen-- 
trals have a quadrangular base of attachment, longer than broad. 
' I have also observed the caudal pore in liématulus. Z. arboreus has the 
longitudinal furrows, but on account of the transparent tissue of the foot I. 
find it difficult to distinguish any caudal pore. 
In Z. ligerus there are well-marked lines running obliquely towards the 
centre of the base of the foot, where is an extremely narrow line, repre-- 
senting, no doubt, the locomotive disk. The other characters of Zonites 
are present in the species. . 
