92 



mantle when about to suspend its function of calcification^ expands itself 

 into several digitations^ of considerable length in some species, each secre- 

 ting a massive claw, which it ultimately fills with calcareous matter, the 

 hinder one being tlirown over the spire so as almost to conceal the primitive 

 gro\i'th of the shell from the observer ; the mantle then withdraws, and 

 subsiding in wrinkles, deposits that richly coloured layer of corresponding 

 wrinkled enamel with wliich the columella and aperture are always adorned 

 at maturity. 



The Pterocera, or ' Spider Shells ', are few in number, but well charac- 

 terized by their distinctions of colour, and the number and growth of their 

 claws ; they are all inhabitants of the tropical seas. 



Species. 



1. aurantia, Lain. 5. millepeda, La)n. 8. rugosa, Sow. 



3. chiragra, id. 6. ixuiltipes, Besli. 9. scorpio, Lam. 

 :]. eloiigata,* Swain. 7. pseudo-scorpio, Lam. 10. triincata, id. 



4. lambis, Lam. 



Figure. 



Pterocera multipes. pi. 8. Fig. 40. Shell, showing the digitated ex- 

 pansion of the Hp, and wrinkled surface of the aperture. 



Genus 6. STROMBUS, LinncBus. 



Animal ; similar to that of Rostellaria, and Pterocera. 



Shell ; ohlovg -ovate, emarginated and recurved at the base ; spire 

 conical, somewhat turreted ; lip expanded, not digitated, atid 

 simiated toioards the base; aperture oblong, rather narroiv, 

 slightly emarginated at the upper part. 



Regarding the soft parts, the Strombi are identical with the Rostellariai 

 and Pterocera already described, and the peculiarities of which it is un- 

 necessary here to repeat ; but the shell presents an uniformity of character 

 sufficiently distinct from either to merit attention. The base is not pro- 



* I cannot agree with M. Deshayes in the propriety of naming this shell " Pterocera novem 

 dactylh "; the noun-ablative is ungranimatical in the sense required by the binomial form of 

 nomenclature. Chemnitz was undoubtedly the first describer of the species, and a very charac- 

 teristic figure is it accompanied with ; but, as was almost invariably the case with his precursor 

 Martini, he omitted to distinguish it by any specific name. The words above quoted, form part 

 of Chemnitz's description,- — " Sirombv.^ novem dadyhs insfnicliis", S:c. , and Svvainsou is 

 therefore justly entitled to the priority of having named the species. 



