Occasional Papers of tlic Museum of Zoology 39 



Altitude Greatest diameter Height aperture Diameter aperture 



32.2 mm. 91 (29.3 mm.) 72 (24.8 mm.) 53 (17.1mm.) 



24.6mm. 91 (22.4mm.) 78 (19.2mm.) 52(i2.8mm.) 



Ampullaria patula Reeve (1856)/ catemacensis, new 

 subspecies 



Figs. 2, 3, 4 and 7 



Twenty-five specimens from Lake Catemaco (H, vii, d). 



Shell thin, translucent, rimate; ground-color yellowish to 

 olive-green or dark brown (rich amber by transmitted light), 

 with 25 to 40 darker brown, spiral bands or lines of varying 

 widths, sometimes with a broadish band of creamy yellow 

 just below suture; surface marked with fine growth-wrinkles, 

 crossed by regularly spaced, delicate, more or less beaded 

 wrinkles, 2 to 3 mm. apart, and by microscopic, wavy ridge- 

 lets, so as to give the shell a beaded appearance under the lens ; 

 spire very low (somewhat eroded and pitted at very tip) ; 

 whorls 4 or 5, rapidly expanding, more or less flattened above, 

 each with the sutural edge sloping up over the preceding whorl 

 so as to give, with the sharply marked, somewhat undulate 

 suture, the impression of being flattened over it ; last whorl 

 greatly inflated, so as often to about equal in diameter, as 

 viewed from above, all of the others combined; aperture very 

 large; peristome slightly thickened within, but with edge 



1 Dr. Bryant Walker, to whom I sent the accompanying figures of 

 this form, writes : "Your figure certainly looks very much like Reeve's 

 patula. Curiously enough, Sowerby in his recent revision of Ampul- 

 laria {Pr. Mai. Soc, VIII, p. 345) seems to have omitted any refer- 

 ence to it. I have four lots in the collection labelled 'patula.' One 

 from the Amazon has got misplaced and I have not been able to find 

 it. The other three evidently belong to the same species, whatever it 

 may be. One lot from 'Brazil' are dealer's specimens, and I know 

 nothing of their history. The other two came from New Granada. 

 They come from Rolle. The 'typical' form is banded and has the 

 interior dark brown, but the aperture is not so expanded as in your 

 shells, and the apex is higher than in Reeve's figure. The largest 

 speciinen measures 30.5 x 25 mm. ; tip of apex eroded." 



