57 



Genus Amphidgsma. 



Amphidesma pulchrum. Amph. testd ovali, pallidd, superficie 

 concentrice striatd ; inths albidd, purpureo-varid ; latere postico 

 breviore ; margine anticd inclinatd, striis nonnullis radiantibus, 

 strias incrementi decussantibus : long, l-rx), lat.^\, alt. 1 poll. 



Hah. in Sinu Caraccensi^ AmericEe Meridionalis. 



This species resembles Amph. variegaium, Lam., in form j it is 

 white within, very prettily mottled with purple. — G. B. S. 



Genus Marginella. 



Marginella Ctpr^eola. Marg. testd ovali, asperd, purpureo-ni- 

 gricante ; spird brevisshnd, obtusd ,- anfractu ultimo superne ven- 

 tricoso, lined dorsali Icevi ; labio externo incrassato, involuto, intiis 

 denticulato ; labio columellari transversim plicato : long.-^,^, lat. 

 ,V poll. 

 Hah. sub lapidibus et in locis arenosis ad littora Acapulcae et 



Sanctae Elense. 

 A most interesting species, inasmuch as it appears to be the link 

 connecting Marginella with Cyprcea: though covered nearly ail over 

 with a fine asperity, it has nevertheless a polished surface j the spire 

 is very small, and the mantle of the animal must have been almost 

 equal on both sides, since there is a nearly central dorsal line which 

 is quite smooth and free from the asperity which covers the remainder 

 of the last volution. — G. B. S. 



Marginella Frumentum. Marg. testd ovali, politd, pallescente, 

 lineis undulatis per series tres dispositis pictd ; spird retusd, aper- 

 turd longitudine testes; peritremate acuto, Icevi; columelld infrh 

 plicis nonnullis: long. tV> ^at. j-,r, paulb minus, poll. 

 Hab. ad oras Americae Meridionalis. (St. Elena and Salango.) 

 A very pretty little species, dredged in from eight to ten fathoms 

 with a sandy bottom. — G. B. S. 



Genus Chiton. 



* Ligamento margin is laevi. 



Chiton pusillus. Chit, testd minimd, obovatd, albicante ; dorso 

 elevato ; valvis intermediis angustis, minutissime punctulatis, areis 

 lateralibus subdistinctis ; valvd posticd majori, vertice centrali, 

 postice inclinato : long. -^, lat. -j^Ty poll. 

 ■ Hab. ad littora Peruvise. (Pacasmayo.) 



Distinguished from all the other Chitons by the comparative height 

 and proportions of the posterior valve, which has a central vertex in- 

 clined backwards. 



Found on a coral reef in seventeen fathoms water nine miles from 

 land. — G. B. S. 



Chiton Grayii. Chit, testd oblongd, pallidd, rufescente fuscoque 

 varid ; valvd anticd, valvarum intermediarum areis lateralibus et 

 valvce posticce ared jwsticd radiatim granoso-striatis ; arearum la- 

 teralium marginibus anticis elevatis, posticis crenulatis ; valvarum 

 intermediarum areis centralibus et valvce posticce ared anticd ob- 



