AMASTRA. 137 



d\ No dull or figured outer cuticle, but the 

 shell often variegated; ovate or oblong. 



Metamastra. 



d l . Outer cuticle when present not figured ; 

 Shell turrited or pyramidal. Paramastra. 

 c 1 . Embryonic whorls generally costate and car- 

 inate, flat; outer cuticle frequently mottled or 

 figured with angular lines; shell ovate or ob- 

 long-conic, dextral. Amastra. 

 c 2 . Embryonic whorls delicately costulate ; shell 

 sinistral, dark or dull colored, without zigzag 

 lines or spots. Heteramastra. 



Arrangement of Species. 



The Amastrse are grouped by islands in the descriptive 

 text of this work, as a more convenient arrangement than 

 one strictly natural. This plan often separates forms closely 

 related; therefore a classified list is given below. This clas- 

 sification differs in some important details from that of Pro- 

 fessor Hyatt's manuscript. This would not be especially 

 significant were it not that the systematic relationships of 

 the forms affect fundamentally our zoogeographic concep- 

 tions. It has therefore been deemed necessary to give in full 

 the senior author's classification, with his deductions regard- 

 ing the migrations of the several groups. See Appendix B. 



Systematic List of Amastrce. 

 Genus AMASTRA H. & A. Adams. 



Subgenus KAUAIA Sykes. 

 A. kauaiensis Newc. Kauai. 



Section ARMIELLA Hyatt. 

 A. knudseni Bald. Kauai. 



Subgenus CYCLAMASTRA Pils. & Van. 



[The genera Pterodiscus, Planamastra and Armsia are tan- 

 gents of this group.] 



(SpJiaerica Series.} 



A. cyclostoma Bald. Kauai. A. obesa Newc. Maui. 

 A. sphferica Pease. Kauai. A. agglutinans Newc. Maui. 



