224 PROCEEDINGS OF THE ACADEMY OF 



outer margin of the membrane ; both of the cusps bear distinct 

 cutting points, the outer one small, the inner one narrow, blunt, 

 almost as long as the base of attachment. There are no distinct 

 marginals, the laterals decreasing in size as they pass off laterally, 

 those at the edge of the membrane (fig. c) having one large inner 

 cutting point, and several, outer, irregular smaller ones. I have 

 oriven a a group of centrals and laterals, b a group of laterals, and 

 c an extreme lateral or marginal. 1 



I have had no opportunity of examining M. Kieneri. 



Genus BULIMXILUS, Leach. 3 



Jaw thin, arcuate, ends but little attenuated ; no median pro- 

 jection to the cutting edge ; anterior surface with numerous, 

 separated, delicate ribs, denticulating either margin, 

 Fig. 6G. sometimes the upper median ones running obliquely 

 ^rfjjK towards the median line, or even arranged en chevron 

 >'W \/X as * n M acroceramus t with an upper median triangu- 

 9 VJ lar compartment. 



jaw of The jaw of B. dealbatus is here figured. It is quite 



Bulimuhts 



dealbatus. arched. That of B. Marielinus and alternatus is of 

 the same t3'pe. I have given on plate XVI., fig. 12, 

 a more enlarged view of one end of the jaw of B. sufflatus, to 

 show more accurately the character of the ribs. 



The lingual membrane of the genus as now received varies too 

 much to allow of a general description. It can only be said that 

 the marginal teeth are quadrate, not aculeate. I will here simply 

 confine myself to describing the membrane of the only one of our 

 species of which I have preserved the lingual membrane. 



Fig. (57 shows the general arrangement of the teeth on the mem- 

 brane of B. dealbatus, the characters of the individual teeth being 

 shown in pi. XV., fig. 7. There are 94 rows of 25 1 25 in one 

 specimen examined. Another had 20 1 20 teeth, with 14 per- 

 fect laterals. 



The central tooth has a base of attachment longer than wide, 

 with but little expanded lower lateral angles, its lower margin 



1 Similar dentition is found in M. turricula, Pfr., of Cuba. See below, 

 pi. XX, fig. 9. 



2 I use this generic name only temporarily. As suggested by von 

 Martens, it must eventually be restricted to those species whose dentition is 

 like that of B. Quadelupemis, the type of the genus. 



