ANGITREMA. 13 



to Tennessee and Northern Alabama. These exceptions are 

 A. verrucosa and armigera, both of which extend northward 

 into Indiana, inhabiting the Wabash River.* 



Unlike the species of Pleurocera, those of this genus are with 

 one or two exceptions well defined and easily distinguishable 

 one from another. 



SYNOPSIS OF THE SPECIES OF ANGITREMA. 



A. Body-whorl with a coronal of tubercles, with frequently an inferior 



row revolving parallel with it. 



1. A. geniculata, Hald. 3. A. subglobosa, Lea. 



2. A. salebrosa, Conr. 4. A. Tuomeyi, Lea. 



B. Body- whorl encircled above the aperture by two rows of tubercles, of 



which the inferior one is the more prominent. 



5. A. Juyana, Lea. 



C. Body-whorl with a central row of tubercles. 



6. A. rota, Reeve. 9. A. Wheatleyi, Tkyon. 



7. A. armigera, Say. , 10. A. stijgia, Say. 



8. A. Duttoniana, Lea. 



D. Body-whorl with numerous tubercles, in parallel rows. 



11. ^1. lima, Conk. 12. A. verrucosa, Raf. 



A. Body-whorl icith a coronal of tubercles. 

 1. A. geniculata, IIaldejian. 



LitJiasia geniculata, Haldeman, Suppl. to Xo. 1, Mouog. of Limniacles, Oct., 1840. 



Bi.vNEY, Check List, No. 299. 

 Anculotus geniculatus, Halileman, Jay, Cat. Shells, 4th edit., p. 276. Hanley, 



Conch, misc.. t. 5, f. 41. Reeve. Monog. Anculotus, 1. 1, f. 7. 

 Leptoxis geniculata, Haldeman, Bkot, List, p. 24. 

 Lithasia genicula. Lea, WHEATLEY, Cat. Shells U. S., p. 28. Adams, Geuera, i, 308. 



•It is a curious fact that many of tlie tuberciilate and plicate species of Strepomatidse 

 Inhabit the Wabash, so far north of their peoRrapliical centre. Mr. Lea informs me that 

 the same curious distrlbutlou prevails witli certain southern species of i'nioniJie. 



