UNIVALVES. 



PLATE IV. 



Genus. BIPLEX. 

 Character. A spiral shell, tuberculous, having two folds or sutures, dividing 

 the shell into two parts : the shell rather flattened from the front of the mouth to 

 the back ; the cheek of the mouth, formed by one of the folds ; the mouth round ; 

 the beak small. 



Species. 



No. 1. Biplex Rosa. Shell whitish-brown, richly adorned with tubercles, and 

 rugous furrows ; the folds channelled on one side, but not on the other ; 

 mouth red, and deeply carunculated, of a pleasing rose colour. A native 

 of New Caledonia, and very rare. From the Author's Museum. 



No. 2. Biplex Australasia. Shell red, marked on the folds with dark streaks 

 of brown ; mouth gray, and the teeth sometimes double ; the shell is some- 

 times covered with a skin or epidermis of a pale green colour, as in No. 4 

 of this Plate, which makes it appear like a different shell, though in reality 

 the same. This shell is a native of New Holland and Van Diemen's Land, 

 and is now generally known. 



No. 3. Biplex tuberculus. Shell of a reddish brown, richly covered with 

 pointed tubercles, sometimes found very large. It is elegantly adorned 

 with ridges of beaded tubercles, and forms altogether a rich and pleasing 

 character ; it is, however, exceedingly common, and is brought generally 

 from the Cape of Good Hope and the neighbouring coasts. 



No. 4. A variety of No. 2, and described under the former head. 



No. 5. Biplex perca. Shell pale amber colour, richly adorned with tubercles 

 and ridgy spines ; the mouth of a pale purple. This exceedingly rare and 

 beautiful shell is in the Cabinet of Mr. Jennings, of Chelsea, and was sup- 

 posed, till lately, to have been unique ; but another is now known to be in 

 the possession of Mr. Spurritt, and although not well preserved, confirms 

 the species. The fancy and imagination which are displayed in the sin- 

 gular and fantastical form of this shell are surprising, and can with dif- 

 ficulty be conceived. The series of beads is curiously broken off in the 

 centre, and the fins or spines certainly resemble those of the perch, from 

 which circumstance we have given it the name of Biplex perca. 



REMARKS. 



This description will most probably close the curious and interesting family of Biplex, of 

 which no great variety has hitherto been discovered, amongst the recent shells ; nevertheless, 

 a curious fossil shell of this genus, something like No. I, has lately been discovered, in the 

 Museum of Mr. Parkinson. 



