MAZATLAN UNIVALVES 211 



?Par3 = Piliclium, Forbes <^ H(nil.=Jot]nai, Phil Eandh. Conch. 

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

 H. Sf A. Ad. Gen. vol. i. p. 461 : non Forbes, Athen. 1849, 

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



Tliis genus is a part of the Scutella of Brod. (tlie remainder 

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

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

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

 of Echinoderms. 



269. Scutellina navicelloides, n. s. 



S. t. ohlongA, lateribm subplanatis, valde inaquilaterali ; 

 apice terminali, sed a margine remoto ; tenui, subdiaphana, 

 albidd, epidermide tenuissima cinerea induta ; liris exilliinis 

 radiantibus et eoncentricis, subaqxiaUhus, creberrimis, confertim 

 decussatd, ad intersectiones subnodosis ; interstitiis quadratis; 

 margine a liris radiantibus vix crenulato ; columella (tit in 

 " Navicelld" ) planatd, arcuatd. 



One specimen only of this beautiful and very distinct species 

 was found by INIr.Darbishire : the apex was imfortunately 

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

 place is nearly determined by the sculptiire. The margin is 

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

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

 Hub.— Ma.zdMan ; 1 fresh sp. from burrow of Lithodomus, in 



Spondylus calcifer ; L'pool Col. 



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

 bishire, Esq. 



Family GADES^IAD^. 



This family was placed among the Pulmol)ranchiata, next to 

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

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

 and Acma>a, by Philippi, 1853 : next the Patellida;, after 

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

 1850, and S. 8f A. Adams, 1854. The animal is gill-bearing, 

 while that of Siphonaria is pidmonated. The shell has no 

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

 left of the head, and generally very small. 



