Occasional Papers of the Museiun of Zoology 



41 



Wheatley Collection, at the A. N. S. P., are two shells labeled 

 A. patula Reeve, Mexico, which are smaller specimens of the 

 brown color-form. The original description and figure of 

 Reeve fits quite well the light color-form, but none of my 

 specimens are completely imperforate, although the young 

 specimens are more nearly imperforate than the larger ones. 

 This subspecies appears to be a considerately larger shell than 

 Reeve's patula. One young specimen is of about the same size, 

 but is quite different in shape, as shown in the table of 

 dimensions. 



The jaw-plates of this form are quite like those of A. HageU 

 lata or of A. Hagellata helizensis, although none of my speci- 

 mens were as regular nor had as well-defined cutting edges as 

 those shown in the figure of F. and C. (1890). The radula of 

 A. patula cateniacensis (fig. 8) is very similar, but shows minor 

 and apparently qitite constant differences (5 radulae exam- 

 ined). The middle cusp of the central tooth is much larger 

 and is not so sharp and angular; the lateral cusps are also 

 larger and better defined, and are spatulate in shape, while 

 those of flagellata are more nearly triangular. These lateral 

 cusps do not appear to have the tendency to split up into 

 smaller cusps, as noted under the latter species. The first 



1 The original description gives no dimensions; these taken from 

 figure. 



