MAZATLAN UNIVALVES 211 
?Pars=Pilidium, Forbes & Hanl.=Jothia, Phil. Handb. Conch. 
p. 200:=Iothia, Gray in rs. Grays Fig. Moll. An. p. 93: 
H. & A. Ad. Gen. vol. i. p. 461: non Forbes, Athen. 1849, 
(=Lottia, err. typ.) teste Woodw. 
This genus is a part of the Scutella of Brod. (the remainder 
constituting the genus Broderipia, Gray, of the family Stoma- 
telline,) 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, 7. S. 
S. t. oblonga, lateribus subplanatis, valde inequilaterali ; 
apice terminali, sed a margine remoto ; tenui, subdiapkand, 
albidd, epidermide tenuissimd cinered induta; liris exillimis 
vradiantibus et concentricis, subequalibus, creberrimis, confertim 
decussatd, ad intersectiones subnodosis ; interstitiis quadratis ; 
margine a liris radiantibus vix crenulato; columelld (ut in 
* Navicella”) planaté, arcuatd. 
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 ealcifer ; L’pool Col. 
Tablet 1016 contains the specimen, presented by R. D. Dar- 
bishire, Esq. 
Famity GADINIAD. 
This family was placed among the Pulmobranchiata, next to 
Siphonariade, when the animal was only known by Adanson’s 
notice, Gray, 1847: in the same company, between Cecum 
and Acmea, by Philippi, 1853: next the Patellide, after 
Philippi had published a description of the animal, by Gray, 
1850, and H. & 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. 
