110 Dentition of Pulmoiiate Mollushs. - 



ing beyond the base of attachment ; marginals bicuspid, cusps short, bluntly 

 rounded, the inner one, as usual, the longer, each bearing short cutting 

 points. 



Stylodon. 



I have shown H. militaris, Pfr., placed in this genus by 

 Ton Martens, to be a Xanina. 



Stylodon Studeriana, Fer. Seychelles. Consul Pike. 



Jaw stout, strongly arched, ends but little attenuated, blunt; anterior sur- 

 face without ribs ; there are, however, a few coarse, broad, vertical wrinkles. 

 One jaw had a slightly developed median projection to its cutting edge. 

 another has no approach to a projection. 



Plate YIII, fig. M, shows the lingual dentition; teeth 69-1-69, with about 

 22 laterals on each side. There is considerable resemblance to the dentition 

 of Merope fringUla described below. The cutting points on centrals and 

 laterals are, however, more pointed. There are no side cusps or cutting 

 points to centrals or inner laterals ; the outer laterals and marginals have 

 very oblique, broad, bluntly trifid cutting points. 



Dentellaria. 



In this genus, the presence or absence of ribs on the jaw is 

 not a reliable generic character. ' 



I have examined a large proportion of the known species. 

 The jaw varies somewhat, so that each description should be 

 studied. There seems a tendency to a median projection to the 

 cutting edge, and to the presence of rib.-. D . pachygastra, Gray, 

 has seven decided ribs and no median projection ; orbiculata, 

 For., has traces of ribs and no median projection; Isabella, 

 Per., has decided ribs, and no median projection: dentiens, 

 Fer., has dec : ded ribs and no median projection; nucleola, 

 Rang., has one decided rib and a median projection: ladia has 

 eight decided ribs; formosa, Fer., lias no ribs, but a strong- 

 median projection: perplexa, Fer., has obsolete ribs and median 

 projection : lychnncJni.s, same as last : punctata. Born, has 

 median projection and decided ribs : Josepliince, Fer., is strongly 

 arched, has no ribs, but a median projection. 



The species agree in their dentition. 



Dentellaria orbiculata, Fer. 



Jaw striated, thick, slightly arched, ends squarely truncated; cutting 

 edge irregular, showing traces of the ends of subobsolete ribs, no median 

 projection. (PI. XVI, fig. W.) 



