MAZATLAN UNIVALVES 359 



GENUS ALVANIA, Bisso. 



In this section are deposited certain turrited Eissoidae, with 

 tumid whirls. They do not however correspond with the genus 

 as denned by H. $ A. Ad. Gen. vol. i. p. 330. 



Cingula, pars, C. 13. Adams. 



I 412. ? ALVANIA EXCUEVATA, n. s. 



?A. t. tenui, turritd, elongatd, purpureo-fuscd, pupaformi, 

 marginibus spirce excurvatis ; anfr. viii. quorum ii. primi pur- 

 purei, Iceves, apice planato ; dein iii. tumidiores, bi- seu tri-cari- 

 nati ; reliqui subplanati, sculpturd minus expresses ; superficie 

 valde irregulariter cancellated; costis obtusis, scepe obsoletis, 

 circiter xx., ad peripheriam evanidis ; liris spiralibus guarum 

 plerumque iii. spird monstrantur, circa basin (injuniore inter- 

 dum Icevem) subangulatam circiter iii. ; interstitiis Jiaud impres- 

 sis, nunc liris nunc costis superantibus ; aperturd subovali, 

 subquadratd ; labro tenui ; labio tenuissimo, rimulam umbilica- 

 lem vix 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. 

 Hab. Mazatlan ; rare, off Chama and Spondylus ; IS pool CoL 



Tablet 1709 contains 8 sp. varying in age, colour and sculp- 

 ture. In one the sculptured layer is entirely removed, and the 

 shell is only known by its shape. 



413. ALVANIA EFFUSA, n. s. 



A. t. "A. excurvata" simili, sed solidiore, apice acutiore, 

 spird regulari, anfr. tumentibus, normaliter cancellatis ; costis 

 circiter xx. extantibus, ad basin evanidis, a liris spiralibus 

 circiter xiii. tuberculatis ; interstitiis et suturis valde impressis ; 

 basi effusd, striulis paucis axin solidam versus ; aperturd 

 oblong d ; labro solido, inter dum 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 ; L'pool Col. 



Tablet 1710 contains the specimen. 



