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. 
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 forms of irregular spicules given by Kélliker (7 4) of Paramuricea 
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 coenenchym 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 hy Professor Studer, but are 
spined and warted instead of bemg 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°5-15 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 Prumnoisis 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. PRIMNOISIS GROUP. 
C. grayi (Wright), N. Atlantic,400 fms. 
C. ornata aa Nova Scotia, 250 fms. 
C. palme (W. & 8.), Canary Islands, 
1125 fms. 
C. philippinensis (W. & 8.), Philippines, 
82 fms. 
P. antarctica (Studer), Kerguelen, 60 fms. 
P. antarctica (W. & 8.), Prince Edward 
Island, 310 fms. 
P. antarctica (Hickson), McMurdo Bay, 
20-120 fms. 
P. sparsa (W. & §.), Prince Edward 
C. nuda (W. & §.), Fiji, reefs. 
C. paucispinosa (W. & %&.), 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. 
Island, 86 fms. 
P. rigida (W. & 8.), Rio de la Plata, 
600 fms. 
P. capensis (Studer), C. of Good Hope, 
50 fms. 
P. ambiqgua (W. & §&.), Kerguelen, 
10-80 fms. 
P. ambigua (Hailes), Lifu, 10 fms. 
P. ramosa (Thomson & Ritchie), 74° 8., 
22° W., 161 fms. 
P. delicatula (Hickson), W.Q., 25-30 fms. 
