genera Ceratoisis and Primnoisis which were placed by Professors Wright and Studer in the 

 subfamilies Ceratoisintr and Mopseince" 1 . 



This view is supported by an argument which should be read carefully by those interested 

 in the discussion, but is too long to be quoted here. The present writer believes, however, that 

 the family Isidcc was ably handled by Wright and Studer, and flnds himself unable to agree 

 with the eminent authority quoted above. 



The intergradation of spicules is very wide spread among the Alcyonaria, and yet there 

 are often certain dominant forms of spicules that are quite characteristic of definite groups, and 

 therefore available for systematic purposes and form good zoological characters s . 



The spicules of the Ceratoisidince are of two general types. i st . True spindles, either with 

 verrucae or comparatively plain or needle-like. These may be slightly forked or bind at one end, 

 but this does not alter their essential character. 2 nd . Flattened spindles which are often bar-like with 

 rounded ends, or with ends enlarged forming a lengthened hour-glass, or biscuit-form. These may 

 approach the form of scales rather than of spindles. Even in such cases their edges are smooth, 

 not ctenate nor with branched processes, although they may be beset with minute thorny points. 



These spicules seem to me to be quite distinct from those found in the genus Primnoisis, 

 which has the characteristic scales of the primnoid gorgonians, with branched processes or finely 

 ctenate edges, often imbricating on the calyx walls. 



This difference is strikingly shown in Plate IX of the Challenger Alcyonaria, where 

 figures i to 5 represent spicules of Acanella, one of the Ceratoisincr; and figures 6 to i i all 

 representing species of Mopseincr. Or compare Plate Va, figures i to 9, all of Ceratoisidiiia-, 

 with Plate IX, figures 6 to 11, of spicules of Mopseina:. It seems to the writer that it would 

 be difficult to show greater contrasts than are found not only in these figures, but also in slides 

 of spicules from specimens of Ccratoisidincc on the one hand, and Mopseince on the other. 



It is true that Hicksox's Ceratoisis spicata (loc. cit., p. 7) at first seems to form an 

 intergrading link between these subfamilies; but it appears to me that this is more seeming 

 than real. This writer describes the spicules, in part, as follows : 



"The calyces are covered with an armature of overlapping scales, some of which are 

 triradiate, others irregular in form". 



According to this description and the figures none of these spicules show any real 

 approach to the form of the characteristic spicules of Ceratoisis. Moreover the writer says: 



"In the character of the axis it is closely related to Primnoisis" . 



The calyx spicules resemble closely some of the thorny scales of the primnoid genus 

 Caligorgia, for instance. 



The present writer, therefore, would place Hicksox's Ceratoisis spicata in the genus Prim- 

 noisis, calling it Primnoisis spicata (Hickson), and retain the subfamilies adopted by Wright 

 and Studer, modifying, how-ever, their subfamily diagnoses as follows: 



I s i d i n ae : — Ccenenchyma thick ; calyces inserted ; spicules densely tuberculate spindles, oval 

 radiate forms, heads, doublé heads, etc. 



1 National Antarctic Expedition. Natural History, Vol. VII, Ccelentera Alcyonaria, 1907, p. 4. 



2 See the discussion of this point by the writer in his Report on the Muriceida: of the Siboga Expedition. 1910, p. 5. 



