140 



THE OPIIIURIDiE 



23. Ophiactis Savignyi (M. & Tr.). 



Lyman : Challenger, Vol. V., Opluuroidea, p. 115 



One specimen from Acapulco. 



24. Ophiactis profundi n. sp. 



Plate VI. Figs. 46. 



m 



Diameter of disk, 6 ram. ; width of arm close to disk; 1 mm. ; length of 

 arms^ c. 5 times the diameter of the disk. One very large^ axe-shaped 

 mouth papilla on each side ; the one at the apex below the teeth triangular^ 

 with a more or less distinct peak within. The lower teeth more or less ser- 

 rate, the upper ones rounded. Mouth shield about as broad as long, almost 

 rhomboidal, an angle within and without ; the sides more or less re-enteringly 

 curved, the outer sides most so ; all the angles rounded. It is somewhat 

 hollowed in the middle. Side mouth shields with outer end much wider 

 than inner end, where they meet. 



First ventral plate very small, its outer end much narrower than the 

 inner end ; laterals and inner edge slightly concave. The following ventral 

 plates a little wider than long, in mutual contact almost to the end of the 

 arm, where they become more elongated. Sometimes, however, they are 

 separated by a little naked space on the inner joints. They are polygonal, 

 inner end truncated (or with an angle), outer side limited by three rather 

 straight lines, which make two obtuse angles; the middle part of the outer 



r •■ 



side is usually a httle concave ; sometimes the whole outer edge is curved ; 

 inner and outer laterals re-enteringly curved ; they are a little hollowed in 

 the middle. Side arm-plates with spine ridge rather prominent, meeting 

 above from about the 5th joint. Dorsal plates very broad, twice as broad as 

 long, usually all separated; however, the side arm-plates do not meet on 

 the inner joints, there being a little naked space which separates them. The 

 dorsal plates have outer edge rounded, a very obtuse angle within, and 

 lateral sides slightly rounded. Arms rather flat, not wider outside the disk. 

 There are constantly six arms. 



Disk covered by small, smooth, rather thick, overlapping scales, among 

 which the primary plates are not distinct. No spines on the disk. The 

 radial shields about as long as half the radius of the disk, narrow, with 









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1 ■ 



t 



V 



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