PACIFIC COAST SPECIES, 



129 



A. Towsendiana 



var. 



ptychophora. 



This is the most abundant siiocios, ospocially along the coast, where, 

 unlike most of our American forest snails, it frequents pn, 102 

 open prairies, among the fern. It is particularly abun- 

 dant on low sandy bars just above high tide, which are 

 covered with a deep, rich deposit of shell marl, and have 

 been formerly favorite caui])ing-grounds of the Indians. 

 These places, being very productive, are much cultivated 

 by the whites, and immense numbers of this animal's shells are found 

 when the grass and bushes are fir^t burnt off. They continue to live 

 in potato fields in the same places, -The bare face of Cape Disappoint- 

 ment, fronting the ocean, is also a locality. I did iiot lind this species 

 about Puget Sound. (Dr. J. G. Copper, P. K. 11. Eep., 376.) 



Jaw as usual ; 9 ribs. .^^j^ 



The lingual membrane (Terr. MolK;^ V, Plate IX, Fig. Q) has GO-l-GO 

 teeth. Another membrane had 40 1-40 teeth. The variety j>fi!/(7/(/- 

 2)hom (Plate XV, Fig. X) has similar c-ntition. The species is peculiar 

 in having decided side cutting pointstto central and lateral teeth, and 

 side cusps to the laterals. 



The genitalia are figured (Terr. MolJ., V, Plate XIV, Fig. A). The 

 accessory gland of the epididymis is composed of several acini of dif- 

 erent sizes. The genital bladder is l(^Vgthened, oval, having a very 

 short, stout duct. At the opening of the penis sac there is a decided 

 enlargement, perhai)s of the nature of a prepuce or prostate. The vas 

 deferens enters the penis sac below its apex. The retractor muscle is 

 at the apex of the penis sac. There seems no accessory organ, the 

 genitalia being reduced to their simplest type, and thus widely differ- 

 ing from the allied species. 



FKr 103 



Ai'ioaata cxarata, Peeifi-er. 

 Shell umbilicated, dei)ressed -conic, rather solid, mnlleated and 

 wrinkled, yellowish, with one chestnut baud ; spire 

 rather acute, conic; whorls 7, equally coh^wex, grad- 

 ually increasing, the last broader, rounded^ scarcely 

 falling in front, narrowed around the open moderate 

 umbilicus; aperture oblique, broadly lunate; peri- 

 stome with a light white thickening, the terminations scarcely con- 

 verging, the right slightly expanded, the columellar triangularly dilated 

 above and widening. Greater diameter 30, lesser 25™™ ; height, 

 16'"™. 



1749— Bull. 28 9 



A. exarata. 



