Entomological Society. 229 



Ch. discors, MutonS; Racket. Ch. punctulatus, Mat on. Ch. scptcm- 

 valvis, Mont. Ch. corallinus, Risso. 



** Margin with ovate imbricate scales. 

 Callochiton evanidus. Chiton evanidus, Sow. III. f. 139. 



3. ISCHNOCHITON. 



Valves thin ; posterior valve entire , the plates of insertion very 

 thin, smooth-edged, of the central valves each with a single notch ; 

 margin covered with very small imbricate scales. 



* Scales of mantle transversely grooved. 



Ischnochiton textilis. Chiton textilis, Gray = Ch. longicymba, 

 Blainv. 



Ischnochiton limaciformis. Chiton limaciformis. West Indies. 

 Ischnochiton Magdaliensis. Chiton Magdaliensis, Hinds. 

 Ischnochiton alatus. Chiton alatus, Sow. Philippines. 



** Scales of mantle minute, granule-like. 



Ischnochiton marginatus. Chiton marginatus, Mont. Ch. cine- 

 reus, Lowe, Z. J. 



4. Leptochiton. 



The valves rounded, thin ; posterior valve entire : the plates of 

 insertion rudimentary, without any notches on either the terminal 

 or central valves. Mantle covered with granular scales. 



Leptochiton cinereus. Chiton cinereus, Montague — Ch. asellus, 

 Lowe, Zool. Jour. var. white, Chiton albus. 



Leptochiton Hanleyi. Chiton Hanleyi, Bean. 



Leptochiton cajetanus. Chiton cajetanus, Poli. Lepidopleurus 

 cajetanus, Risso. 



Should the form of the plates of insertion of any specimen not be 

 sufficiently seen, they may be easily made visible tbrough the inner 

 side of the mantle by their being soaked a few hours in a weak solu- 

 tion of caustic potash, but care should be taken that they are not left 

 too long in soak, nor the solution be too strong, otherwise the margin 

 will be dissolved. But should the valves be wished to be kept sepa- 

 rate, this is the best way of separating them, as the plates of insertion 

 are cleaned, and not broken, as they are likely to be if taken from the " 

 mantle. I may remark that the number of notches in the plates of 

 insertion is sometimes, but as far as I have observed, very rarely, 

 liable to variation ; in one specimen of Chiton Boivenii I have observed 

 that the plate of insertion of the last valve but one has two notches 

 on one side, but the normal single one of the genus on the other. 



ENTOMOLOGICAL SOCIETY. 



August 3rd, 1846. — Thomas Marshall, Esq., Vice-President, in the 



Chair. 



Among the donations were a number of Arpedium subjmbescens, a 

 rare species of Staphylinidce, sent by A. H. Haliday, Esq., for distri- 

 bution among the members. 



