608 THE VOYAGE OF H.M.S. CHALLENGER. 



exceeding 11 mm. in length. The innermost twelve or fourteen actinal spines on the 

 adambulacral plates are modified in shape in a remarkable manner. They are robust, 

 about 5 mm. in length, decreasing as they approach the disk, and have a large, flaring, 

 truncate extremity, the component rods becoming enlarged and fusiform at a definite 

 distance from the end, which produces the appearance of a superadded, composite, flower- 

 like head to the shaft. 



The actinostome is larsre and measures 12 '5 mm. in diameter in a disk 20 mm. in 

 diameter. The mouth-plates are small and insignificant, and slightly prominent at their 

 aboral end. Their armature consists of one small spine on the adoral margin, invested with 

 a thin membranous sheath extended into a vermiform sacculus, the whole about 2 - 5 mm. 

 in length, and bearing numerous minute pedicellariae. On the actinal surface of each 

 plate are two spinel ets with greatly prolonged sacculi, one behind the other, and forming 

 two pairs on each mouth angle, the anterior pair measuring about 5 - 5 mm., and the posterior 

 pair somewhat less. The sacculi are crowded with microscopic pedicellarise. 



The madreporiform body, which is prominent and subtubercular, is situated at the 

 margin of the disk, and nearly on the curvature uniting the abactinal surface and the 

 lateral wall. 



Colour in alcohol, a bleached ashy white, with a slight flesh-coloured shade on the ovarial 

 regions. 



Localit)/. — Station 24. North-west of St. Thomas, Virgin Islands. March 25, 1873. 

 Lat. 18° 38' 30" N., long. 65° 5' 30" W. Depth 390 fathoms. Pteropod ooze. Surface 

 temperature 76°'0 Fahr. 



Remarks. — This form is very nearly allied to Brisinga endecacnemos ; in fact, owing 

 to the fragmentary nature of the material at my disposal, I felt great hesitation at first in 

 ranking it as a distinct species. A careful and comparative study of the specimens, how- 

 ever, has led me to believe that this stej) is fully warranted, and that Brisinga cricophora 

 may be distinguished by the narrower and more prominent annular ridges with small 

 widely spaced spinelets ; by the presence and character of the sacculi crowded with pedi- 

 cellariae ; by the more limited position of the tegumentary spicules ; by the more elongate 

 and less inflated ovarial regions ; by the relatively broader and more depressed rays ; by 

 the relative proportions of the actinal and lateral spinelets ; by the remarkable form of the 

 actinal spinelets on the adambulacral plates at the base of the ray, and by the character of 

 the armature of the adambulacral plates and mouth-plates. 



5. Brisinga armillata, n. sp. (PI. CX. figs. 1-3). 



Rays seven. R = 240 mm.; r = 9 mm . R > 26 r. Breadth of a ray at the base, 

 4-5 mm. ; at the widest part of the ovarial inflation, 7'5 mm. (measured at 24 mm. from 

 the disk) ; at 100 mm. from the disk, 4*5 mm. 



