360 MAZATLAN UNIVALVES 
414, ALVANIA TUMIDA, 2. Ss. 
A. t. ventricosd, albo-fuscd, solida; anfr. v. tumentibus, 
subequaliter cancellatis ; costis haud obtusis circiter xxu. trans- 
versis, a liris spiralibus intersectis, nodosis ; liris vil., quarum 
ill. spiram transeunt, una umbilicum satis magnum definat ; 
interstitiis quadratis ; aperturd subrotundatd, labro varicoso, 
labio tenutore. 
Differs from all varieties of A. excurvata in its very tumid 
growth, umbilicated base, and thickened lip. Long. °057, 
long. spir. ‘034, lat. °033, div. 40°. 
Hab.—Mazatlan ; 2 dead sp. off Spondylus ; L’pool Col. 
Tablet 1711 contains one specimen. 
415. PALVANIA ————, sp, ind. 
Tablet 1712 contains a wnite, rather solid shell, with very 
tumid whirls and a round mouth. It might pass for a Scalaria, 
but has no ribs; or for an Aclis, but the apex is dextral. One 
whirl has perished ; the remaining seven measure /ong. ‘048, 
long. spir. ‘03, lat. °027, dev. 30°. 
Hab.—Mazatlan ; 1 sp. off Chama; L’pool Col. 
Genus CENGULA, lem. 
H. &§ A. Ad. Gen. vol. i. p. 334.—Cingula, pars, C. B. Ad. 
416. ?CinguLa ————-, sp. ind. 
Tablet 1713 contains a short, broad, white, smooth, rather 
solid shell, with flattened whirls, of Odostomoid appearance ; 
but the apex appears dextral. The peritreme is continuous 
and not plaited. It has five whirls, and measures long. °053, 
long. spir. *03, lat. °033, div. 43°. 
Hab—Mazatlan; 1 sp, off Chama; L’pool Col 
Genus HYDROBIA, Hart. 
Sturm, Deutsch. Faun. vi. 5, p. 47, 1821.— Phil. Hand. Conch. 
p. 168.—H. & A. Ad. Gen. vol. i. p. 335. 
Leachia, Risso, 1826.—Paludestrina, Orb. 1840. —Paludinella, 
Lov. Midd. (? = Paludinella, Pfr.) 
Rissoa, pars, auct. 
