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166 



THE OPIIIUmDiE. 





44. Ophiacantha cosmica Lym. 



Plate XV. rigs. 1-3 



Lyman ; Challezigor Opliiuroidca, p. 194, Plate XIII. Tigs. 13-15. 



Of this species there are several specimens from Stations 3360, 1672 f. ; 

 3381, 1772 f. ; 3382, 1793 £ ; and 3414, 2232 f. 



Though in general accordance with Lyman's description^ there are sev- 

 eral small differences to be noted. The first ventral plate sometimes has the 



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form shown in our figure, but usually that seen in Lyman's figure ; those 

 beyond have a more or less distinct median cut in the outer edge. Tentacle 

 scales usually on the inner joints only ; in Lyman's figure they are of a 

 form uncommon in Ophiacantha^ and are inserted on the side of the ventral 

 plate, but this is not in accordance with his description^ so the figure may be 

 incorrect in this respect. The spines of the disk (Fig. 3) are about 0.8 mm. 

 long. Lyman says they are '^composed of five or six thorns, of different 

 lengths, soldered side by side." This description seems not to be inconsist- 

 ent with the figure here given. They continue on the 6-8 inner dorsal 



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plates, along their outer edge, not spread on the plates, as on Lyman's 

 figure. The arm-spines are shorter than in Lyman's specimens, the longest 

 being scarcely as long as two arm-joints, and they are finely but distinctly 

 thorny. These differences we do not think to be sufficient to found a new 

 species or variety upon. The most important difference may be that in 

 regard to the arm-spines ; but their number is the same. Of far greater 

 importance evidently is the feature of the papillae outside the true mouth 

 papillo3, in which they correspond, a feature also found in 0. rosea Lym. and 

 0. sciikda Lym., and which gives a rather curious aspect to the mouth. 

 One specimen has only four arms. 



45- Ophiacantha paciflca n. sp. 



Plate XV. Figs. 4-6, Plate XVI. Fig. 11. 



Diameter of disk, 12 mm. ; width of arm close to disk, without spines, 

 2 mm.; length of arms, about five times the diameter of the disk. 3-4 rather 

 large, more or less pointed mouth papillae on each side 5 that on the apex 

 usually very broad. Close to the first ventral plate is seen something like 

 a papilla (at the adradial side of the outer mouth tentacle), but it is not a 





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