PULMONAKY GASTEKOPODS. ' 43<) 



stripes of white and red, comes from the coasts of Asia and America. 

 Strombus luliuanus (Fig. 298) is fawn-coloured, marked with white, 

 and externally the right edge is red and striped ; inside the columella 

 is shaded purple and black. 



Strombus cancellatus, the trellised Strombus (Fig. 299), is small 

 in size and white in colour. Strombus thersites is also represented 

 (Fig. 300). 



PTEROCEBAS. 



The Pteroceras, from Tnepov, wing, and /cepas, horn, in many respects 

 resemble the Strombi. They are distinguished from them chiefly in 

 this, that the right edge developes itself with age in long and slender 

 digital spines more or less numerous, the numbers of which vary 



Fig. 301. Pteroceras Scorpio Fig. 302. Pteroceras millepeda 



(Linnaeus). (Linnasus). 



according to the species. The Pterocerse are found in the seas of 

 both hemispheres, their vulgar denomination being sea-spiders or 

 scorpions. A glance at the illustrations (Fig. 301, Pteroceras scorpio ; 

 Fig. 302, P. millepeda; Fig. 303, P. chiragra; and Fig. 304, 

 P. lamlis) will satisfy the reader as to the general correctness of this 

 designation. 



The genus Pteroceras, whose remarkable form is so well calcu- 

 lated to excite our admiration, has yet another attraction : the colour- 



