702 Modification of the Apex in Gastropod 3Iollusks. 



but the post-nuclear whorls are strongly ribbed and spirally 

 striate. The lateral outline of this species shows a graceful, 

 rounded curve. A half dozen perfect specimens examined. 



Stromlius minimus Linii6. 



The apex of this species is similar to that of S. gigas, has two 

 and a-half rounded whorls, but is much broader and more pyra- 

 midal. Two specimens examined. 



Family PLANAXID.E. 



Genus PL.A1VAXIS Lamarck. 

 Planaxis planicostata Sowerby. (Fig. 54.) 



Apex small, pointed, smooth, shining, consisting of three and 

 a-half regularh^ increasing whorls. The color is a deep wine-red. 

 The post-nuclear whorls are coarsely spirally ribbed. The lateral 

 outline of the apex of this species shows a sharp pyramid. A 

 number of specimens examined. 



Family YERMETID^. 



Genus TERMICUL,ARIA Lamarck. 

 Vermicularia spirata Philippi. (Fig. 55. ) 



Apex small, knob-shaped, smooth, lustreless, consisting of one 

 and a-half whorls rapidly increasing in size ; color yellowish ; 

 post-nuclear whoi'ls spirally ribbed and carinated. This species 

 shows a wonderful degree of constancy in the form of the nucleus. 

 About twenty specimens examined. 



Family LITORINID^. 



Genus LITORIXA Ferussac. 

 Litorina aspera Philippi. 



The nucleus of this species seems to be in all respects like that 

 of fig 42, and consists of two and a-half hyaline whoi'ls. 



The following species do not differ in the form of the nuclear 

 whorls : 



Liitorina scabra Linne. Nucleus yellowish in color. 

 Liitorina consper§a Philippi. Nucleus purplish in color. 

 Litorina philippii Carpenter. Nucleus hyaline. 

 Liitorina scutulata Gould. Nucleus brownish in color. 

 Liitorina patula Gould. Nucleus brownish in color. 

 Liitorina palliata Say. 

 liitorina olbtusata Linne. 



