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. ro&mingeri 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. rcumingeri, 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 opposite the crural processes. The 
external form of these species is more or less appressed in the upper part 
of the shell, with a flattened beak. The principal forms known are Cryp- 
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 
recurved portion being quite short. It does not, therefore, differ essentially 
from Waldheimia except in extent. The third form differs from Wald¬ 
heimia only in the possession of the connecting dorsal band. 
