MAZATLAN UNIVALVES 309 
Genvs ALVANIA, Risso. 
In this section are deposited certain turrited Rissoide, with 
tumid whirls. They do not however correspond with the genus 
as defined by H. g A. Ad. Gen. vol. 1. p. 330. 
Cingula, pars, C. B. Adams. 
412, PALVANIA EXCURVATA, 2. S. 
2A. t. tenui, turritd, elongata, purpures: fused, pupaformi, 
marginibus spire excurvatis ; anfr. Vill. quorum ll. primi pur- 
purei, leves, apice planato ; dein iii. tumidiores, bi- seu tri-cari- 
nati; reliqui subplanati, sculpturad minus expressa ; superficie 
valde irregulariter cancellatd ; costis obtusis, sepe obsoletis, 
circiter xx., ad peripheriam evanidis ; liris spiralibus quarum 
plerumque il. spirad monstrantur, circa basin (in guniore inter- 
dum levem) subangulatam circiter i1.; interstitiis haud impres- 
sis, nune liris nune costis superantibus ; apertura subovali, 
subquadrata ; labro tenui; labio tenuissimo, rimulam umbilica- 
lem vie monstrante. 
This shell, in its regular growth and markings, reminds us 
of Turritella goniostoma. About 100 specimens were found, 
but most of them were extremely imperfect. Long. °112, 
long. spir. ‘077, lat.*038, div. 25°. 
Hah.—Mazatlan ; rare, off Chama and Spondylus; L’pool Col. 
Tablet 1709 contains 8 sp. varying in age, colour and sculp- 
ture. In one the sculptnred layer is entirely removed, and the 
shell is only known by its shape. 
413. ALVANIA EFFUSA, 2. Ss. 
A. t. “A. excurvate” simili, sed solidiore, apice acutiore, 
spira regulari, anfr. tumentibus, normaliter cancellatis ; costis 
circiter xx. extantibus, ad basin evanidis, & liris spiralibus 
circiter xill. tuberculatis ; interstitiis et suturis valde impressis ; 
bast effusd, striulis paucis axin solidam versus ; apertura 
oblonga ; labro solido, interdum varicoso ; labio inconspicuo ; 
umbilico nullo, 
Only one specimen was found of this beautiful species, which 
is distinguished from A. tumida by its very elongated shape, 
and from A. excurvata by the above characters. In sculpture 
it resembles Phos. Long. ‘115, long. spir. ‘077, lat. ‘042, div. 22°. 
Hab.—Mazatlan ; 1 sp. on Spondylus; Z’pool Col. 
Tablet 1710 contains the specimen. 
