690 Modification of the Apex in Gastropod Mollusks. 



Pamily HARPID^. 

 Genus HARPA Lamarck. 

 Harpa minor Lamarck. (Fig. 15.) 



Apex large, rounded, smooth, shining, consisting of two and a- 

 half whorls, regularly increasing ; the last part of the third whorl 

 is lost in the first post-nuclear whorl ; the nuclear whorls are 

 without a carina and perfectly smooth, while the post-nuclear 

 whorls are marked by spiral strise and strong, elevated ribs. The 

 apex is of a beautiful pink color. In the five perfect specimens 

 examined there is no variation from this type. 



Harpa conoidalis Lamarck. (Fig. 16.) 



The apex is large, and consists of three and a-half whorls, but 

 in all other respects is like that of minor. The apical whorl in 

 both species is very flat. Three specimens examined. There is 

 sometimes a lightly impressed spiral line encircling the second 

 nuclear whorl near the suture of the following whorl. 



Harpa articularis Lamarck. 

 Harpa ventricosa Lamarck. 



Both of these species have the nuclear whorls of the same num- 

 ber and shape as those of conoidalis. In fact, so far as the apex 

 goes, the species cannot be separated. Three examples of each 

 species have been examined. 



Harpa noliilis Lamarck. 



But a single, barely perfect specimen of this species is before 

 the writer, and, so far as can be made out, it is identical with the 

 preceding species. The whole group of harps seems to the writer 

 to be very closely connected, and it is very doubtful if there are 

 over three or four valid species in the genus. The genus is prob- 

 ably not old enough, geologically, to have acquired stable differ- 

 ential characters. 



Family MARGINELLIDiE. 

 Genus MARGI]VEL,L,A Lamarck. 



Marginella pruiium. Gmelin. (Fig. 17.) 



Apex small, flatly rounded, smooth, shining, consisting of one 

 and a-half whorls, rapidly increasing. Both nuclear and post- 

 nuclear whorls are smooth and shining, and the nuclear whorls are 



