MAZATLAN UNIVALVES 211 



?Pars = Pilidium, Forbes fy Hani. = Jothia, Phil. Handb. Conch. 

 p. 200 :=Iotliia, Gray in Mrs. Grays Fig. Moll. An. p. 93 : 

 S. & A. Ad. Gen. vol. i. p. 461 : n'on Forbes, Athen. 1849, 

 (=Lottia, err. typ.) teste Woodw. 



This genus is a part of the Scutella of BrocL (the remainder 

 constituting the genus Broderipia, Gray, of the family Stoma- 

 tellinse,) of which the name was altered to Scutellina by Dr. 

 Gray in consequence of its preoccupation by Lam. for a genus 

 of Echinoderms. 



269. SCCJTELLINA STAVICELLOIDES, n. S. 



S. t. oblong a, lateribus subplanatis, valde incequilaterali ; 

 apice terminally sed a margins remoto ; tenui, subdiapJiana* 

 albidd, epidermide tenuissima cinerea induta ; liris exillimis 

 radiantibus et concent rids, subcequalibus, creberrimis > confertim 

 decussata, ad intersectiones subnodosis ; interstitiis guadratis ; 

 margine a liris radiantibus vix crenulato ; columelld (ut in 

 "Navicelld"} pianola, arcuala. 



One specimen only of this beautiful and very distinct species 

 was found by Mr. Darbishire : the apex was unfortunately 

 broken, in detaching the shell from extraneous matter, but its 

 place is nearly determined by the sculpture. The margin is 

 concave ; the shell resting on its anterior and posterior ex- 

 tremities. Long. '22, lal. "14, alt. "06. 

 Hab. Mazatlan ; 1 fresh sp. from burrow of Lithodomus, in 



Spondylus calcifer ; Upool Col. 



Tablet 1016 contains the specimen, presented by B. D. Dar- 

 bishire, Esq. 



FAMILY GADIJSTIAD^E. 



This family was placed among the Pulmobranchiata, next to 

 Siphonariada?, when the animal was only known by Adanson's 

 notice, Gray, 1847 : in the same company, between Ca3cum 

 and Acmsea, by Philippi, 1853 : next the Patellida3, after 

 Philippi had published a description of the animal, by Gray, 

 1850, and H. fy A. Adams, 1854. The animal is gill-bearing, 

 while that of Siphonaria is pulmonated. The shell has no 

 interruption in the muscular scar for the slit, which is at the 

 left of the head, and generally very small. 



