ALCYONAEIA. 5 



of C. spicata are covered with little wart-like projections. The spicules of the 

 ccenenchym of C. spicata are irregular branched plates very much like the scales 

 of my Ceratoisis ramosa and the Primnoisis group as figured by Professors Wright and 

 Studer (14), and as they appear in the two species from the Antarctic collection. 



The spicules of Ceratoisis spicata are indeed characteristic of the old genus 

 Ceratoisis in so far as they project as spines from the calyx, but also characteristic of 

 the genus Primnoisis in so far as their minute structure is concerned. It might be 

 suggested that Ceratoisis spicata ought to be made a type of a new genus intermediate 

 between the other two, but the general character of the axis is so similar to that of the 

 two genera that this course is not to be justified. I have examined carefully the axis of 

 all the species in the collection and of my species from the Cape, and cannot find any 

 characters to distinguish them. The internodes in all cases are hollow, marked 

 externally by shallow longitudinal grooves, but not by spines or tubercles as in 

 Acanthoisis. The branches arise from the calcareous internodes, and the first node of 

 each branch is always some distance from the origin of the branch. 



There is never any difficulty in distinguishing the axes of Ceratoisis and Primnoisis 

 from those of any other genus of the family, but I can find no characters to distinguish 

 the axis of a Ceratoisis from that of a Primnoisis. When dead specimens with no 

 calices or ccenenchym are examined, it is possible to identify them as belonging either 

 to the genus Primnoisis or Ceratoisis, but it is quite impossible to determine to which of 

 these genera they belong. It is quite possible, for example, that the form recently 

 described as Primnoisis ramosa by Messrs. Thomson and Ritchie (11) may really be 

 more closely allied to species hitherto included in the genus Ceratoisis. I would 

 therefore venture to propose that in future the two genera, Ceratoisis and Primnoisis, 

 be merged into one, and that the genus Ceratoisis thus enlarged be defined simply as : 

 "Isidse, with long, calcareous, hollow internodes, scored with shallow longitudinal 

 grooves, short horny nodes, branches arising from the calcareous internodes." 



The name Primnoisis should, in my opinion, disappear from our system, but for 

 convenience sake I have retained the name in brackets in those species here described 

 which, under the older system, would unquestionably have been placed in the genus 

 Primnoisis. 



Ceratoisis (Primnoisis) delioatdla. 



(Plate II., figs. 11 and 12.) 



Locality :— W.Q., September 8th, 1903. No. 12 hole, 100 yds. S. of Hut Point. 

 25-30 fathoms. 



The specimens on which this species is founded are in the form of a tangled mass 

 of delicate branches attached to sponges and worm tubes. There appear to be no main 

 stems, nor can 1 find any bases of attachment in the substance of the sponges. 

 Whether a thick stem was left behind by the dredge or not I cannot say, but the 

 tenuity and delicacy of the branches are sufficient to justify the specific name I have 

 given to the species. The diameter of the thickest stems I have measured is ' 65 mm. 



