BULIMULUS. 387 



BULIMTJLUS, Lkach. 



Animal helicifonn ; mantle subccntral ; other characters as in Patula, etc. 



Shell oblonjij; aperture longitudinal, cdentulate ; peristome thin ; margins un- 

 cipKil ; ooluinella integral. 



In the present state of our knowledge I think it best to leave our species 

 simply under the above generic name, without attempting to group them into 

 subgenera. As suggested by von Martens, Bulimulus must eventually be re- 

 stricted to those species whose dentition is like that of B. Guadelupensis, the 

 type of the genus. All of ours whose dentition is now known agree with that 

 species in this respect, except B. Dormani. 



Jaw thin, arcuate, ends but little attenuated ; no median projection to the 

 cutting edge ; anterior surface with numerous, separated, deli- 

 cate ribs, denticulating either margin, sometimes the upper Fig. 269. 

 median ones running obliquely towards the median line, or 

 even arranged en chevron as in MacroceramuSy with an upper 

 median triangular compartment. 



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

 That of B. Marieluius, ScJiiedeanuSj and alternatus is of the 

 same type. I have given on PI. XVI. Fig. 1 2 of Proc. Phila. Acad. Nat. Sci., 

 1875, a more enlarged view of one end of the jaw of B. suffiatus, 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 have below described the membrane of the only 

 ones of our species of which I have examined the lingual membrane. 



The general arrangement of the teeth on the membrane of B. dealbatus is 

 as in Patula, the characters of the individual teeth being shown in PI. X. 

 Fig. E. There are 94 rows of 25 — 1 — 25 teeth in one specimen examined. 

 Another had 20 — 1 — 20 teeth, with 14 perfect laterals. The central tooth 

 has a base of attachment longer than wide, with but little expanded lower lat- 

 eral angles, its lower margin incurved, its upper margin broadly reflected. 

 The reflection is large, and has subobsolete side cusps, bearing well-developed 

 cutting points, and a short, stout median cusp, bearing a short, stout cutting 

 point not quite reaching the lower margin of the base of attachment. The 

 laterals are of the same general form as the centrals, but are larger, broader in 

 proportion, and are rendered asymmetrical by the suppression of the lower 

 inner angle of the base of attachment, and inner side cusp and cutting point. 

 The marginal teeth are but a simple modification of the laterals, formed by the 

 proportionally greater development of the reflection in comparison with that 

 of the base of attachment, and the greater development of the cutting points. 

 On the extreme marginals the cutting points are shorter and much blunter. 



The dentition of Buliimdus alternatus is figured on p. 203 of L. & Fr.-W. 



