Of the Order Ophiuridae. ]47 



Genus Ophioderma, Miiller and Troschel 

 Nearly allied to Pectinura is the genus Ophioderma of Miiller and Troschel 

 (Wiegmann's Arcbir, 1840), founded on the Ophiura lacertosa of Lamarck, 

 a species not uncommon in the Western Mediterranean, though rare in tli« 

 ^gean, and with which many exotic forms have been confounded. The habit 

 is that of Ophiura, the characters those of Pectinura, from which it mate- 

 rially differs in having four conspicuous genital pores in the inferior inter- 

 spaces, two near the mouth, and two towards the margin. The fossil Ophiura 

 Egertoni belongs to this genus. The Mediterranean species is prettily varie- 

 gated with orange, white, black and gray, and has a disc which is sometime* 

 nearly an inch broad, with rays nearly five times as long as the breadth of the 

 disc. It lives in from 10 to 20 fathoms water on various kinds of bottom. 

 The characters of the genus, revised, will stand thus : — 



Corpus orbiculare, squamosum, granulosum, ad peripheriam radiatum ; radiis simplicibus 

 squamosis ; disco in radiorum origines prolongate, infra poris genitalibus viginti ; squa- 

 mis radiorum lateralibus adpressis, in marginibus superioribus spiniferis, spinis simpli- 

 cibus ; ossiculis ovarialibus parvis, oralibus pectinatis. 



Sp. Ophioderma lacertosa. 



O. radiis convexiusculis ; squamis superioribus transverse oblongis : laterali- 

 bus 8- spiniferis : inferioribus quadratis. 



Ophioderma lacertosa, Mull. 8$ Tros. 

 Ophiura lacertosa, Lamarck. 

 Ophiura squamata et Rondeletii, Risso. 

 Asterias ophiura, Delle Chiaje. 

 Diam. disci T ^ unc; long, radiorum 3 unc. 



Genus Ophiomyxa, Miiller and Troschel. 



This genus was constituted for the reception of an unnamed species in the 

 Paris and Vienna collections. The characters are remarkable. The skin of 

 the discs and arms is smooth, and when recent, slimy, coriaceous, and un- 

 provided with scales. There are but two genital pores in each interspace, and 



v2 



