36 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



There are 7 superomarginal and 8 or 9 inferomarginal plates on 

 the largest specimens, and 7 of each on two smaller examples from 

 station 5491. The cribriform organ is relatively larger in the larger 

 specimens. The spinelets of each distal border, to the number of 

 about 20, are united by a thin membrane, but the others are free. 

 The angle between the lateral and ventral border is more abrupt 

 in the large specimens, possibly because the organ occupies a larger 

 amount of the first plate, there being scarcely any of it left bare. 

 Koehler found 5 marginals in the type. In hatheri there are 5 to 7. 

 The superomarginals nearly always have a second or accessory 

 spinule, and on the second and third plate, sometimes elsewhere. 2 ac- 

 cessories. One of the smaller specimens has 3 on the second plate. 

 The primary spines are more prominent in small than in large 

 examples. The spines of the terminal plate are as described by 

 Koehler. 



Large examples have 15 (instead of 11 of the type) pairs of 

 adambulacral plates and 15 pairs of tube feet to each ray. The 

 adambulacral plates are hollowed out on the furrow margin as 

 described by Koehler, but instead of there being constantly 2 furrow 

 spinules, a few proximal plates have only 1; in one of the large 

 specimens the 6 or 7 distal plates have only 1 spinule. This same 

 specimen has 2 spinules to each mouth plate, in addition to the 

 median unpaired marginal spine, but the other large specimen has 

 3 on all plates except one, where there are 4. The 2 small speci- 

 mens have usually 3 lateral mouth spines, occasionally 4. The 

 type of vaneyi has 2, and hatheri has 4 or 5. The mouth plates are 

 very prominent actinally and each is produced into a winglike process 

 adjacent to first adambulacral. 



The plates of the actinal intermediate areas are rather loosely 

 joined, some of them slightly imbricated. About 30 of the plates 

 bear a central slender spinelet, very similar to the spinelets of the 

 cribriform organs, although a trifle longer. The median interradial 

 area is not devoid of spinelets as in S. p^ilonotus. The intermediate 

 plates extend to the fifth or sixth adambulacral plate. 



The peristome contains widely scattered microscopic rods with a 

 few perforations. These are more numerous in the lip. A small 

 piece of the wall of the stomach did not have any calcareous deposits. 

 A piece of the dorsal integument from the ray (where there were 

 neither papulae nor spinelets) contained scattered microscopic 

 plates, some very small with 2 or 3 perforations, and apparently 

 just beginning to be formed; others larger and with very irregular 

 periphery; still others nearly circular with 12 to 25 perforations. 



Type-iocality.—G\\\i of Oman, lat. 21° 53' N.; long. 57° 43' E.. 

 833 to 733 fathoms (Koehler). 



