32S 



DISCOVERY REPORTS 



Nearly all the specimens from St. WS 821 have the buccal plates or the dorsal arm- 

 plates, or both, irregularly divided. The specimens from the other stations have both 

 buccal plates and dorsal arm-plates undivided. The great variation which exists 

 on this point in the present species has been repeatedly emphasized by Koehler 

 {op. cit.). 



An important fact is to be noted in this species — or at least in the present specimens — 

 viz. that the genital slits are quite short, not extending beyond the first lateral plate. 

 But in continuation of the genital slit there are, in the larger specimens, a number of 

 flat, irregularly arranged granules (recalling to some degree genital papillae) (Fig. 420). 

 This has an important bearing on the question of the identity of these specimens with 

 Lyman's Ophioglypha inornata and with Liitken and Mortensen's Ophioglypha divisa. 

 Both these species are represented as having long genital slits, continuing to the edge of 



Fig. 42. Homalophhira inornata (Lyman). Part of oral side (a). 

 dorsal side, of type specimen (A). ■ 20. 



6. Part of arm. 



the disk. If that be correct, the present specimens are not identical with them, and must 

 then represent a distinct species. Lately I had an opportunity of examining the type 

 specimen of Lyman's Ophioglypha inornata in the British Museum. I find the genital 

 slits to be quite short, not proceeding beyond the first lateral plate, but, as in the present 

 specimens, there are some granules along the sides of the arms in continuation of the 

 genital slits. PI. Ill, fig. 10 of the Challenger Ophiuroidea is therefore erroneous in 

 regard to the genital slits, and thus far the Antarctic specimens agree with Lyman's 

 inornata. There is, however, one noteworthy difference. In the type of inornata the 

 plates of the disk and arms have a peculiar coarsely granulated appearance (Fig. 42 b), 

 whereas in the Antarctic specimens the plates are quite smooth. If this proves 

 to be a constant difference between the Atlantic-Pacific specimens of inor?iata and 

 those from the Antarctic seas, the latter should evidently form at least a separate 

 variety. 



