18 THE VOYAGE OF H.M.S. CHALLENGER, 



The skeleton presents stout genital plates, with clubbed ends, much as in Ophiura, 

 and having attached a long, thin genital scale broken in two or more pieces. The peris- 

 tomial plates are in two stout pieces, which form together a wide heart-shape. Arm 

 bones as high as wide, with long tops, having a deep longitudinal canal, while then- wings 

 are thin and have sharp edges. In contrast to the delicate imbricated scaling of the 

 disk is the size of the radial shields, which touch each other, are very wide, and have a 

 process inward. (See PI. XXXVII. figs. 4-6.) 



Species of OphiopcBpale not herein described. 

 V Ophiopcepale goesiana, Ljn. (PI. XXXII. figs. 4-6). 



~ Ophiopcepale goesiana, Ljn., Dr Goes, OjiL Of. Kong. Akad., 1871, p. 615; Lym., Bull. Mus. 



Comp. Zool., vol. V. part 9, p. 228. 



West Indies; 100 to 180 fathoms. 



Ophiogona. 

 OpMogona, Studer, Monatsb. Kouig. Akad. Berlin, July 1876. 

 Mouth papillae, about fourteen to each angle. Teeth in a double row ; no tooth papiUse. 

 Disk clothed with fine scales, covered by a soft skin; and without notches in its upper 

 sides, at the basis of the arms. Numerous (3-6) flat tentacle scales, arranged along- 

 transverse pores. Nine short arm spines. Mouth shields long and extending into the 

 interbraehial space, which has two genital openings. 



Species of Ophiogoiia not herein described. 



Ophiogona Icevigata, Studer, Monatsb. Konig. Akad. Berhn, p. 460, July, 1876. 

 Kerguelen Islands ; 120 fathoms. 



Ophiolepis. 

 Ophiolepis, Miill. & Tr., Wieg. Ai'ch., vol. vi., 1840. 



Disk covered with radial shields and stout plates ; each larger one, above, being- 

 surrounded by a belt of smaller ones. Over the base of each arm, a smaU notch in the 

 disk. Genital scales thick and conspicuous. Teeth ; no tooth papillae ; numerous even, 

 close-set mouth papillae. Side mouth shields wide, and nearly, or quite, meeting within. 

 Arm spines short and small, supplementary pieces to the upper arm plates. Two short 

 genital openings, beginning at the sides of the mouth shields. 



As compared with the massive disk plates, the skeleton proper is somewhat slight, 



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