422 PALAEONTOLOGY OF NEW YORK. 



far as observed, is characteristic of the short ventricose shells, usually having 

 their widest portion anterior to the middle, as in T. jucunda, T. simulator, 

 and T. harmonia. Probably the New York forms of T. ramingeri would 

 show this feature could specimens be obtained suitable for cutting. 



The second form of loop is short with the anterior portion sharply re- 

 curved and twisted in the curving. As examples of this form we have T. 

 sullivanti in the figured specimen, and T. ramingeri, from Thunder Bay, 

 Michigan. These forms are rotund or appressed. 



The third form of loop is like that of Waldheimia, but has the crura 

 connected by a band on the dorsal side opjiosite the crural processes. The 

 external form of these species is more or less appressed in the upjier part 

 of the shell, with a flattened beak. The principal forms known are Cnjp- 

 tonella rectirostra, C. planirostra, and C. eximia. 



The first form of loop mentioned is probably of generic importance, as 

 there are several species which show it clearly. The second form of loop 

 is the same as that of the third, with the exception of the dorsal band, the 

 reciuyed portion being quite short. It does not, therefore, difier essentially 

 from Waldheimia except in extent. The third form differs from Wald- 

 heimia only in the possession of the connecting dorsal band. 



