OPHIOMYXIDAE 



245 



angular, adoral shields rather broad, not joining within ; they separate broadly the buccal 

 shield from the first lateral plate. Mouth papillae small, feebly developed. Ventral arm 

 plates distinctly longer than broad, with convex distal edge, joining broadly at least as 

 far out on the arms as they are preserved. Dorsal arm plates very feebly developed, as 

 usual, but covering the whole broad dorsal side between the small lateral plates; they 

 are not divided in two by a transverse line. Arm spines four, short, robust, the lower- 

 most and uppermost ones slightly longer than the two middle ones. One tentacle scale. 

 Colour in alcohol brownish. 



The species is clearly viviparous; not that I have actually found embryos within it, 

 but the eggs are large, ca. o-z-o-t, mm. and yolky, seven to ten eggs in each gonad; and 

 then it is hermaphrodite, there being one male gonad at the adradial side and one 

 or two female gonads at the interradial side of the bursa. As not a single case is known 



Fig. 4. Ophioscolex marionis, n.sp. a, Part of oral side, b, Part of dorsal 

 side of arm. The dotted arch-lines represent the outline of the vertebrae 

 seen through the exceedingly thin dorsal plates. X15. 



of a non-viviparous Ophiurid being hermaphrodite, we may, I think, safely con- 

 clude that this species must be viviparous, as the character of the female gonads also 

 indicates. 



It may be added that no spicules are found in the stomach wall, such as occur in 

 O. niitrix. 



That this species is not very closely related to the other Antarctic species of Ophio- 

 scolex, O. mitrix, is evident enough; a comparison of the figures will show the difi^erences 

 in the shape of the buccal shield, ventral and dorsal arm plates, and the mouth papillae, 

 to which may be added the difference in the number of arm spines, one having three, 

 the other four spines, which makes an important difference within this genus. It would 

 appear that the present species is the nearest related to O. quadrispinus, Verrill, from off 

 Nova Scotia ; this species is, however, scarcely sufficiently well known to allow the dif- 

 ferences between the two species to be indicated ; but it seems that O. quadrispinus has 

 no spines on the disk. 



