A. E. Verrill — N'orth American Ophiuroidea. 319 



A, Caribea (Ljung.) Ver. 



Arm-spines six, rough. Oral papillae four, the two distal ones 

 squamiform. 



It is possible that this species, from the West Indies, 800 to 400 

 fath., is the young of A. olivacea. -In that case the latter name 

 would become a synonym. 



Family, OPHIACANTHID^ Ver. 



Ophiacanthince (sub-family of Aviphiuridce) Ljungman, 1866 ; Liitken, 1869. 

 Ophiacanthiclce Verrill, Ophiur. Bahama Exped., Nat. Hist. Bulletin, v, p. 34, 

 1899. 



The family is characterized by the prominent and highly devel- 

 oped side arm-plates, usually meeting above and below, and by the 

 numerous, usually long, and more or less rough spines, which stand 

 out nearly at right angles to the arm. The spines may be solid or 

 hollow, glassy or opaque, terete or flat. 



The oral papillae are usually rather numerous and form a continu- 

 ous row along the sides of the jaws, but the outer ones may be of 

 lai'ger size or different in form from the others, or clustered, and in 

 such cases they are really the distal oral tentacle-scales. There may 

 be only a single apical tooth-papilla, or there may be two or three, 

 and sometimes there is a large cluster. The first under arm-plate is 

 usually concave or somewhat bilobed within the mouth-slit, and 

 usually bears two vertical flat processes, which sometimes become 

 movable, like oral papillae. 



In some cases the outer oral tentacle-pore is exposed to view on 

 the outer, margin of the jaw, and then it has one, or sometimes 

 several, special oral scales or papillae by its outer side, or partly 

 surrounding it. Some of its scales may be attached to the adoral 

 plate, or even to the first under arm-plate. This plate is usually 

 concave or somewhat bilobed, and usually bears two inner, lateral, 

 scale-like processes, which are sometimes movable and papilliform 

 like oral papillae. 



There is generally a single median acute tooth-papilla at the tip 

 of the jaw, but there may be two or three, and in some cases 

 ( Ophiocamax, Ophiomitra, Ophiotrenia) there may be a cluster of 

 several spiniforra tooth-papillae. These were counted as oral 

 papillae by Mr. Lyman, but when they stand on the dental plate they 

 should be considered as true tooth-pajDillse. 



