3G8 Prof. F. J. Bell on a 



Hydrichtliys^ rather than that Hydriclithys is a parasitic 

 descendant of Velella ; while the acceptance of the last-men- 

 tioned theory would lead us to regard fixed Hydroids like 

 Coryne as likewise descendants of parasitic forms with which 

 they have few resemblances. Indeed, we know next to 

 nothing of the &gg and early growth of either Hydrichthys or 

 Velella. We have at all events found in Hydrichthys a near 

 ally of Velella as far as the Hydroid is concerned, whatever 

 may be the story told by the early history of both. 



There is also another point long since known to those 

 familiar with the literature of the Hydromedusae, which is 

 beautifully illustrated by Hydrichthys. Several naturalists 

 have mentioned or called attention to the resemblance of the 

 Medus£e of Hydroids of very different form. We may have 

 Medusae so nearly related as to be placed in the same geuus, 

 but their Hydroids would otherwise be placed in different 

 genera. In Hydrichthys we have an illustration of this prin- 

 ciple. The Medusa is similar to Sarsia, but there is only a 

 remote likeness between the attached Hydroid Hydrichthys 

 and Coryne the Hydroid of Sarsia. If a special student of 

 the Hydroids was called upon to identify the parasitic Hydroid, 

 he would consider its zoological distance from Coryne very 

 considerable ; but a study of the Medusa would lead him to 

 a very different opinion of its zoological position. 



Do these facts of a difference in the form of the Hydroids 

 of allied Medusiform gonophores, or vice versa, as sometimes 

 happens, the diversity of Medusae derived from similar Hy- 

 droids, mean anything morphologically '? The question is an 

 interesting one, and admits of several interpretations, which, 

 however, it is not my purpose to consider at present. 

 There is one thing which has a bearing on the subject, which 

 I wish in closing to say in this connexion, viz. : the true affini- 

 ties of the majority of genera of Camjjamdarian or Tuhularian 

 Hydroids, or of LcptomeduscB and Anthomedusce derived from 

 the same, cannot he definitely made out until both Hydroid and 

 Medusa are studied together. 



XLIX. — Notice of a remarkable Ophiurid from Brazil. 

 By F. Jeffrey Bell, M.A. 



Among the specimens recently collected at Itamaraca, a few 

 miles from Pernambuco, by Mr. Ramage, and forwarded to 



