Occasional Papers of the Museum of Zoology AI 
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. 
Greatest Height Diameter 
Altitude diameter aperture aperture 
Patula 30 98(29.5)  83(25.0)  62(18.5)2 
Catemacensis 
Young 36.5 88 (32) 82(30) 58(21) 
Fig. 2 44.0 102(45)  89(39) 69(30.5) (type) 
51.5 91(47) 77(39.5) 56(29) (not shouldered) 
42 98 (41) 91 (38) 64 (27) 
Mean 44.5 05 84 62 (24 adults) 
Extremes 40-51.5 QI—102 77-91 56--69 
The jaw-plates of this form are quite like those of A. flagel- 
lata or of A. flagellata belizensis, 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 catemacensis (fig. 8) is very similar, but shows minor 
and apparently quite 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 
1The original description gives no dimensions; these taken from 
figure. 
