458 BULLETIN 10 0, UNITED STATES NATIONAL MUSEUM 



In Cochlostyla (Prochilus) virgata (Jay) the shell varies enormously 

 in size and shape; it may be elongate-conic or elongate-ovate, slender 

 or gibbose. The whorls may be slightly "rounded or inflated. The 

 suture ranges from poorly defined to strongly impressed. The 

 periphery may show indications of an angulation or it may be inflated 

 and well rounded. The base may be short and inflated and well 

 rounded or produced and but slightly rounded. The aperture may 

 vary from oval to subquadrate; the outer lip may be slightly expanded 

 and reflected or broadly expanded and decidedly reflected and even 

 thickened; the columella may be slender or broadly expanded at its 

 insertion and reflected and appressed to the base without leaving an 

 umbilical chink, or a slight umbilicus may be present. The parietal 

 wall may be covered by a mere film of callus, or the callus may be so 

 thickened as to join the posterior angle of the aperture with the 

 columella. The nuclear whorls may be light or dark or intermediate. 

 The postnuclear whorls are covered by a hydrophanous periostracum, 

 which also presents great variation in coloration. It may be pale 

 yellow or orange tinted or olivaceous or even brownish. The hydroph- 

 anous lines may be narrow, broad, or even fulgurated, vertical, 

 protracted, or retracted. The shell itself, when the periostracum is 

 removed, may be unicolor, bluish white, flesh colored, pale yellow, 

 olivaceous, pale brown, dark brown, or purple-brown; varicial streaks 

 may be present; or the shell may be variously banded with zones of 

 brown and yellow, varying materially in width. The interior of the 

 aperture is bluish white, sometimes more intensely bluish than at 

 others. The peristome is usually of the same color, but in some of the 

 forms it is edged with buff, brown, or purple. The nuclear whorls 

 are well rounded and form a more or less pointed apex. They are 

 smooth, except for lines of growth and the last portion of the last 

 turn, which shows the beginning of fine spiral striations. The 

 postnuclear whorls also show retractively slanting lines of growth, 

 which in some individuals amount almost to threadlike riblets, and 

 the strength of spiral striations on spire and base also shows consider- 

 able variation. There seems scarcely any limit to the degree of 

 variation in the shape and color pattern, and some idea of the range 

 of variation can be obtained by an examination of plates (unfortu- 

 nately not in color). 



On plate 102 I have copied 12 figures representing previously 

 named shells that are now referred here. Figures 1, 5, and 9 represent 

 Bulinus sylvanus Broderip as figured by Reeve in his Conchologia 

 Iconica on plate 9, figures 46a, b, and c. Figures 1 and 2 represent 

 Pilsbry's Cochlostyla {Prochilus) pulchrior, as figured on his plate 16, 

 figures 12 and 13, figure 1 being a copy of one of the specimens of 

 Reeve's sylvanus. Figure 3 is a copy of Jay's Bulimus porraceus, 

 figured in Jay's Catalogue, plate 6, figure 5. Figure 4 is a copy of 



