8 



SYDNEY J. HICKSON. 



such varying forms that it is difficult to describe them in a few words. Some have 

 four or five spokes united together at a central hub, some are irregular spindles, others 

 are forked. The forms of irregular spicules given by Kolliker (7 A) of Paramuricea 

 in his Taf. xvii., 19 and 20, of Mopsea in his Taf. xix., fig. 41, are not unlike some of 

 the spicules seen in my preparations. 



The position of this remarkable species is difficult to determine at present. In 

 the character of its axis it is closely related to Primnoisis, but the spicules are 

 altogether unlike any species of that genus that has hitherto been described. The 

 irregular spicules of the ccenenchym are like the spicules I described in Ceratoisis ramosa 

 from the Cape ; the spicules of the calyx have a remote resemblance to the forked 

 spicules of the calyx of Ceratoisis grandiflora described by Professor Studer, but are 

 spined and warted instead of being smooth. 



In the species attributed to the genus Ceratoisis described by Professors Wright 

 and Studer (14), the internodes vary in length from 15-60 mm. ; in those attributed 

 to the genus Primnoisis they vary from 2 '5-1 5 mm. (in one species only). The 

 length of the internodes of C. spicata varying from 13-20 mm. in length brings it, 

 in this respect, nearer to the Ceratoisis group than to the Primnoisis group, but 

 in Ceratoisis ramosa of the Cape the internodes are only 3-5 mm. in length. It 

 is clear, therefore, that notwithstanding the many resemblances to the Primnoisis 

 group the species is really more closely related to the Ceratoisis group. In any 

 case it forms a connecting link between the two groups which renders it very 

 difficult to regard them any longer as distinct genera. 



In considering this question of the amalgamation of the two genera a glance 

 at the distribution of the species will be of interest. 



CERATOISIS GROUP. 



C. grayi (Wright), N. Atlantic,400 fms. 

 C. omata (Verrill), Nova Scotia, 250 fms. 

 C. palmse (W. & S.), Canary Islands, 



1125 fms. 

 C. philippinensis (W. & S.), Philippines, 



82 fms. 



C. nuda (W. & S.), Fiji, reefs. 

 C. paucispinosa (W. & S.), Japan, 



345 fms. 



C. grandiflora (Studer), Fiji, 975 fms. 

 C. siemensii (Studer), Newfoundland, 



1780 fms. 



C. ramosa (Hickson), Cape, 230 fms. 

 C. spicata (Hickson), McMurdo Bay, 



120 fms. 



PRIMNOISIS GROUP. 



P. antarctica (Studer), Kerguelen, 60 fms. 

 P. antarctica (W. & S.), Prince Edward 



Island, 310 fms. 

 P. antarctica (Hickson), McMurdo Bay, 



20-120 fms. 

 P. sparsa (W. & S.), Prince Edward 



Island, 86 fms. 

 P. rigida (W. & S.), Rio cle la Plata, 



600 fms. 

 P. capensis (Studer), C. of Good Hope, 



50 fms. 

 P. ambigua (W. & S.), Kerguelen, 



10-80 fms. 



P. ambigua (Hiles), Lifu, 10 fms. 

 P. ramosa (Thomson & Ritchie), 74 S., 



22 W., 161 fms. 

 P. delicatula (Hickson), W.Q., 25-30 fms. 



