CA DULUS-G A DILA . 189 



Jamaican Oligocene. This has modern descendants in C. acus of 

 the Gulf of Mexico, and C. panamensis and var. major of the Pan- 

 amic region. It is extremely probable that all the above mentioned 

 forms fall within the limits of one single species. A smaller but 

 allied species, C. singaporensis, occurs in the East Indian fauna. 



The series of smooth species is also represented in the Antillean 

 Oligocene. C. elegantissimus Pils. & Sharp and C. phenax P. & S. 

 belong here. Recent, it has occurred only in the Californian fauna, 

 where C. aberrans Whiteaves and the very closely allied C.fusifor- 

 mis S. & P., and C. hepburni Dall, also similar, are found. 



As to C. dominguensis (Orb.), its characters have been too inde- 

 finitely described to permit a positive location ; and it is likewise 

 doubtful whether C. Icevis belongs to this group or some other; 

 and it may even be non-molluscan. Dentalium corrugatum Cpr. is 

 a young shell of the aunulated C. dentalinus group. 



Key to species. 



I. Shell circularly corrugated toward the apex. 



a. More or less of a short inflation near the larger end ; length 

 7-1 1 mill. ; American forms. 

 b. West American. 



c. Length 7'5 mill., 9 times the diarn. (sculpture 



unknown), West Columbia, perpusillus, p. 190. 



c'. Length 7 mill., 7 -9 times the diam., Panama 



to L. Cal.. panamensis, p. 191. 



c". Length 8-10 mill., 6-7 i times the diam., 



major, p. 192. 

 b. Antillean forms. 



c. Length 7-7'5 mill., 7|-10 J times diam., Oligo- 

 cene of Jamaica, dentalinus, p. 190. 

 c'. Length 8 mill., lOi-11 times the diam.; 

 recent, acus, p. 191. 

 a'. Not inflated near larger end ; less annulated ; length 5*6 

 mill., 7i times the greatest diam. ; Singapore, 



singaporensis, p. 195. 

 II. Shell smooth, not circularly corrugated. 



a. Length 28 mill., 14 times the diam. A doubtful member 

 of the genus. N.-E., Australia, Icevis p. 195. 



a'. Smaller and not nearly so slender ; anterior constriction 

 slight ; West American. 



