40 Prof. Forbcs's Retrospective Comments. 



V. — Retrospective Comments. By Prof. Edward Forbes, 

 V.P.W.S., F.L.S., F.B.S. &c. 

 An absence of eighteen months in covintries where natural-history 

 periodicals have not yet ventured to circulate, and where, while 

 a glimmering notion of the progress continually going on in sci- 

 ence might be gathered from an occasional letter, the published 

 details of what was doing could not be obtained, obliges a natu- 

 ralist to make himself acquainted with a long arrcar of accumu- 

 lated matter wliich it is his duty to learn ere he starts anew. The 

 occupation is however anything but irksome, and those whom in- 

 clination or professional pursuits keep at home can scarcely con- 

 ceive the pleasure of sitting down to turn over the ]iages of three 

 vokmies of unpcrused ^ Annals.^ Under such circumstances too do 

 we sec the progress of things. When in the midst of the scientiiic 

 world, gathering its news day by day, and reading its chronicles 

 month after month, wc are apt to fancy that little is doing and 

 that there is a stagnation of research ; but when the doors of the 

 workshop ha^•e been closed against us for some time, the work 

 which has been made strikes us far more on our return than if 

 we had watched its progress step by step. Such was my feeling 

 this winter on receiving the numbers of the ' Ainials ' which had 

 been published during my absence abroad. Among their contents 

 are many papers and notices, on the subjects of which light may 

 be thrown by stray oljservations from the note-book or by short 

 comments. As they are not a few, I prefer gathering them together 

 in an article to printing them as disjointed remarks, presenting 

 them in chronological order. 



I. In the 45th Number of the ' Annals ' (July 1841) Mr. Has- 

 sall has constituted a genus, Echinocorium, for the reception of 

 Alcyonidium ccliinatum and what he supposes to be its polype, 

 but which is only a species of Corijne attached to the Alcyonidium. 

 Having frequently taken both the zoophytes in question when 

 dredging in the Irish sea, and having carefully examined and 

 drawn them when alive, I can say this without a doubt. The 

 Corrjne is a connnon deep-sea form of that genus, usually of a pale 

 or white colour, and having much shorter tentacula than the Coryne 

 scjuamata. It is by no means constantly associated with the Al- 

 cyonidium, though, from the excellent holding afforded by the 

 latter, it perhaps prefers such a residence, but is also found on 

 the bare surfaces of old shells. The polype of the Alcyonidium 

 echinatum I have never seen, but believe, from analogy, to be as- 

 cidioid. Had Mr. Hassall looked a little closer to his specimens, 

 he would have found that there is no organic connexion between 

 the parasite and its base, and that each Coryne is an indcjicndent 

 animal, capable of detachment without injury. Dr. Johnston, 



