APORRHAIS. 



249 



small, horny, pear-shaped, increasing by semielliptical layers ; 

 nucleus nearly terminal, at the base of the mouth. 



Included, with Strombus, in ''Les Ailees'' of Lamarck. 



Genus APORRHAIS ^ Da Costa. PI. lY. f. 3. 



Shell sculptured with nodulous ribs and fine spiral striae : 

 spire ending in a blunt button-shaped point : luJiorls numerous : 

 mouth angulated : oute7^ lip usually dilated into several digi- 

 tations or wing-like processes, each of which is narrowly and 

 slightly grooved and terminates in an angular point or spike : 

 base forming a shallow and beak-like rudimentary canal. 



A shell-fish so peculiar and common in the Archi- 

 pelago as A. pes-pelecani must have been known to " the 

 father of natural history.^-' He mentions it as one of 

 the univalves possessing an operculum (iTrcKaXv/jufia or 

 irwjjba) which makes such shells bivalve. The muzzle 

 seems to be of an intermediate kind between the snout- 

 like head of Trichotropis and the true proboscis of Pur- 

 pura. The difference of shape in the immature shell 

 was pointed out by Lamarck; and its resemblance to 

 that of Cerithium was urged by Swainson as a reason 

 for merging the last-named genus in the Stromhidce. 



Aporrhais of Aldrovandi and Aporrais of Gualtieri is 

 the Pterocera of Lamarck. Petiver was the first to use 

 the present name in its restricted sense ; and the genus 

 was sufficiently defined by Da Costa. The Aporrhais 

 of Klein was one of the Valuta family. Klein^s genera 

 ought not to be recognized; they are ill- compounded, 

 and much too extensive. In some cases each of his 

 species comprises several modern genera. On the other 

 hand, he calls Murex a class, and divides it into two 



* Probably the diroppaXs of Aristotle, so named from the spHt or rag- 

 ged shape of the outer Hp. 



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