ANATOMY OF AM ASTRIDE. 63 



approximately straight transverse rows. The central tooth 

 is always much narrower than the laterals, and bears a single 

 short cusp which is probably functionless. This is similar to 

 the Achatinidce, a family which differs fundamentally in other 

 characters, such as the pallial organs and genitalia. 



In Carelia, Amastra and Laminella gravida the laterals are 

 of the usual quadrate form, with two cusps. The marginal 

 teeth have two cusps, or the ectocone may be split into two or 

 rarely more denticles. PL 21, fig. 6, Carelia turricula has 1, 

 22, 24 teeth. PI. 21, figs. 1, 2, 3, Amastra gravida. PI. 21, 

 fig. 4, Amastra spirizona. 



Laminella citrina has four or five denticles on the mar- 

 ginals (pi. 21, fig. 8), the teeth otherwise as in Amastra. 



Pterodiscus rex, pi. 21, fig. 7, has 1, 9, 17 teeth in a half 

 row. Like those of Amastra, the marginals have several den- 

 ticles. 



In Leptachatina the marginals are multi-denticulate by 

 splitting of the ectocone, and on the outer ones the mesocone 

 is also split. PL 21, fig. 5, L. labiata. PL 21, figs. 9, 11, L. 

 (Thaanumia) fuscula. The number of teeth is rather small. 

 L. lal}iata having, 1, 11, 23 in a half row, L. fuscula 1, 9, 18, 

 and Pauahia chrysallis 1, 6, 12 teeth, the marginals with five 

 or six denticles. 



The reproductive organs are almost identical in general 

 structure in the species of Carelia, Amastra, Pterodiscus and 

 Laminella which have been examined. The penial retractor 

 is invariably simple, inserted at the origin of the appendix, 

 not the apex of the penis as in the Achatinellidcz. The ap- 

 pendix is always more swollen distally than in Achatinellidcz* 

 The spermathecal duct is short, not long as in Achatinellida. 

 There is a well-developed albumen gland, and the digitate 

 prostate gland is nearly as large as in Achatinella. All of 

 these genera are viviparous, usually carrying several young 

 in the uterus. In Carelia turricula the embryo shell may be 

 12 mm. long, of 4^ whorls before birth. In Amastra the com- 

 parative length of the appendix varies widely. Thus, it is 

 50 mm. long in A. pullata subnigra, 13 mm. in A. aurostoma. 



In Amastrella flavescens (Hawaii), A. badia (Oahu), Cy- 



