170 



THE OPIITURIDiE. 



neath the stumps. On the under side of the disk there are stumps only on 

 the outer part^ on the inner part the scales are naked. Genital scales not 

 distinct. 



Six or five arm-spines^ farther out only four; they do not form a con- 

 tinuous series over the dorsal side of the inner joints. The upper one is 

 much the longest, about as long as tla^ee arm-joints, on the inner part of the 

 arm ; farther out it is not much longer than the others. Downwards they 

 gradually diminish in lengthy the lowest being scarcely as long as one arm- 

 joint. They are feebly thorny, the upper ones almost smooth. One rather 

 largo oval pointed tentacle scale. 



Color in alcohol : gray. 



Ten specimens from Stations 3356, 546 f., and 3393, 1020 f. 



48. Ophiacantha Nomani Lym. 



Plate XVI. Figs. 1-4. 



Ophiacantha Normani. Lyman : Preliminary Ecport of t!ie Challenger Opliiuroidca. Part II. Bull. Mus. 



Conip. Zo61., Yo]. VI. Ko. 2, p. 58. Plate XV. Pigs. 414.-416. 

 O^liiomUra normani. " Cliallengcr Ophinroidea, p. 208. Plate XXVI. Figs. 9-11. 



Of this species there are numerous specimens from Stations 3432, 

 1421 f (one young specimen) ; 3435, 859 f. ; and 3436, 905 f. 



As our specimens show several differences from the figures given by 

 Lymak, we have deemed it best to c^ive fio^ures also. The differences are as 

 follows. 



The mouth papilte are all cylindi'ical in Lyman's figure ; in our speci- 

 mens that on the apex is broad and flat, and sometimes the two adjoining 

 papillae are likewise so. At the pore of the second mouth tentacle there is 

 a more or less distinct small rounded papilla. Sometimes there are more 

 papilla3 crowded at the apex. The mouth shield, according to Lyman, 

 is " a little broader than long," in our specimens it is twice as broad as 

 long, and so it is also represented in Lyman's figure. Its sides are all 

 slightly concave, or the outer sides are straight or a little curved. The side 

 mouth shields sometimes meet within. 



The ventral plates are rather different from those in Lyman's figure, 

 especially the second, which has usually the outer edge a little concave. 



r 



Often all the ventral plates have a Httle re-entering curve or median cut in 



the outer edge. The secoud is about equally broad and long, farther out 



