

R 



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THE OPIIIURIDyE. 



137 



Six specimens from Station 3417; 493 f. One specimen from Station 

 3426; 14G f., differs from the other specimens, its disk covering being thicker 



than common in this species. 



The form of the mouth shields is very variable, the inner part being very 

 different in breadth ; sometimes it is not broader than the outer part, some- 

 times there is a little peak within, sometimes it is broadly rounded ; on the 

 same specimen scarcely two are alike. The radial shields not seldom are 

 wholly separated. 



^.> 



These two species very much resemble O.familiare Koehler.and O.elegans 



Koehler, from the Indian Ocean (67); 0. DiomcdecB the former, 0, variahile 



• 



the latter. They are, however, sufficiently characterized, 0. DiomedecB by its 

 inner ventral plates being in mutual contact, 0. variahile by its curious radial 

 shields. 



/ 



22. Ophiomusium Lymani Wyv. Thomson 



Plate III. I^igs. 8 11. 



, Wyv. Thomson: Depths of the Sea, p. 173, Figs. 33, 33. 

 Th. Lyman, Clialleiigcr, Yol. V., Opliiuroidca, p. 90. 

 « " (76), p. 245, Plate Y. Pigs. 55-57. 



As there is not yet given either a full description or detailed figures of 



this species, it is given here. 



Diameter of disk; 30 mm. ;, width of arm close to disk, 5 mm.; length of 

 arms, 4-5 times the diameter of the disk. Six to seven short, square mouth 



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papilte on each side, making a close line^ and one diamond-shaped (often 

 irregular) at apex of jaw. The outer papilla is somewhat broader than the 

 rest. Mouth shield often irregular, divided in smaller pieces (Fig. 8) ; its 

 appropriate form, however, is that seen in Figure 9 : an acute angle within, 

 outer edge straight, lateral sides deeply restricted, the inner part of the 

 shield being much narrower than the outer; it is somewhat longer than 

 broad. Side mouth shields large, meeting within, the outer end much 



broader than the inner end. 



First ventral plate of a peculiar form : inner edge concave, the corners 

 produced along the sides of the mouth slit; lateral sides straight and outer 

 edge slightly concave, with a little peak in the median line. The two next 

 ventral plates small, pentagonal, with an angle within and outer edge as on 

 the first plate ; lateral sides with a restriction on the middle part for the 



