ANATOMY OF AMASTRID.E. 65 



Fig. 6, Amastra aurostoma. 



Fig. 7, Pterodiscus rex. Male organs and atrium. 



PLATE 17, fig. 2, Amastra cyclostoma. Kauai. 



Fig. 4, Carelia turricula Migh. Kauai. 



Fig. 6, Amastra spirizona. Popouwela. 



Fig. 7, Amastra flavescens. Glenwood, Hawaii. 



Leptachatina resembles Amastra closely in genitalia, ex- 

 cept that the spermatheca duct is longer, though not so long 

 as in Achatinella. Its basal third is enlarged, and the sper- 

 matheca is globular. It is, however, not much more than half 

 as long as the appendix. 



L. ventulus (Fer.), pi. 17, fig. 3. 



L. corneola (Pfr.), Halawa, Oahu. PL 17, fig. 1. 



L. attenuata Cooke, Haleieie, Kauai. PL 17, fig. 5, penis. 



Amastrida* are much more abundant as fossils than the 

 Achatinellidfc, being found in all pleistocene deposits contain- 

 ing land shells, often in prodigious numbers. The extinct 

 species of Leptachatina, Amastra and Carelia are somewhat 

 numerous. 



The classification of Amastrida is given on pp. xx, xxi, of 

 Vol. XXI. Leptachatina and Amastra are the two really dis- 

 tinct primitive stocks, the other groups being satellites of 

 these, and evidently derived from them. Recognizing this, 

 Professor T. D. A. Cockerell proposed to classify the genera 

 in two tribes, Leptachatinini and Amastrini (Science, 1913, 

 p. 256). These groups may be retained as subfamilies, the 

 Lcptachatinincc containing the genera Leptachatina, Pauahia 

 and provisionally Fernandezia, the Amastrina; comprising 

 Armsia, Planamastra, Pterodiscus, Amastra, Carelia and La- 

 mine lla. 



