602 THE VOYAGE OF H.M.S. CHALLENGER. 
The genus Brisinga as now defined is limited to those forms in which the abactinal 
skeleton of the rays is confined to isolated transverse ridges limited to the basal portion of 
the ray, and in which the abactinal membrane is entire, and not punctured by papule. 
Synopsis of the Species included in the Genus Brisinga herein described. 
A. Transverse calcareous ridges prominent and robust. 
a, Rays robust, nine to thirteen in number. Transverse ridges broad and 
robust (15-20 in number). Ambulacral tube-feet not separated by 
two spinelets . : : 5 . ° . 2 . . . coronata. 
b. Rays delicate, eight in number. Transverse ridges thin and high 
(10-12 in number). Ambulacral tube-feet separated by two 
horizontally placed parallel spinelets . ° : ; ; ; A verticillata. 
B. Transverse calcareous ridges moderately prominent or more or less rudi- 
mentary. 
a. Ridges complete. Tegumentary prickles in the abactinal membrane. 
a. Rays eleven in number. Ambulacral tube-feet not separated by 
two equal horizontally disposed spinelets. 
a, Adambulacral armature with three inner spinelets, all small. 
Actinal spines at base of ray needle-like. With 
crowded spinelets on the transverse ridges . ; : . endecacnemos. 
fB. Adambulacral armature with two inner spinelets, one large. 
Actinal spines at base of ray robust, clavate, with a 
coronate extremity. With widely spaced spinelets on 
the transverse ridges . 5 : : 5 - : < cricophora. 
b. Rays seven in number. Ambulacral tube-feet separated by two 
equal horizontally disposed spinelets . A : - . armillata. 
b. Ridges incomplete and more or less rudimentary. No tegumentary 
prickles in the abactinal membrane. 
a. Adambulacral armature with one inner spinelet. Lateral spines 
short. Calcareous ridges feebly developed . : ° : . membranacea. 
b, Adambulacral armature with three or four inner spinelets. Lateral 
spines long. Calcareous ridges rudimentary, never complete : discincta. 
Chorology of the Genus Brisinga. 
a. Geographical distribution :-— 
ATLANTIC: Six species between the parallels of 10° and 70° N. 
Brisinga coronata, off the Lofoten Islands, the west coast of 
Norway, south of Rockall, west coast of Ireland, and west coast of 
Spain. Also in the Mediterranean, dredged by the “Travailleur ” 
and “Talisman” (fide Perrier). Brisinga endecacnemos, off the 
west coast of Norway, between the Faerte and the Shetland Islands, 
off the south-west coast of Ireland, in the Bay of Biscay, west of 
Ushant, and off the west coast of Spain. Brisinga mediterranea, 
between Marseilles and Corsica. *Brisinga cricophora, north- 
