Prof. G. J. AUman's Biological Contributions. 417 



LI. — Biological Contributions. By George J. Allman, M.B., 

 F.R.C.S.L, M.R.I.A., Professor of Botany in Trinity College, 

 Dublin, late Demonstrator of Anatomy and Conservator of the 

 Anatomical Museum, T.C.D. 



[With a Plate.] 



No. I. Description of a new genus of Helianthoid Zoophytes. 



At the York Meeting of the British Association in September 

 1844, I read before the Natural History Section a description of 

 a Helianthoid Zoophyte which I had just discovered on the Irish 

 coast. The subject of the communication I believed to possess a 

 form generically distinct from all hitherto described, but not ha- 

 ving been able since its discovery to procure the works necessary 

 to establish this point with certainty, I refrained at the time from 

 naming it. Since then however I have convinced myself of its 

 claims to a new generic rank, whose limits may be assigned by 

 the following characters : — 



CORYNACTIS. 



Gen. Chae. Body subcylindrical but very mutable in figure, 

 adhering by an expanded base. Tentacula capitate, contractile, 

 surrounding the mouth in one or more concentric series*. 



Species unica, C. viridis. PI. XI. 



Hab, Near low water mark in the pools left by the retiring 

 tide. Crook Haven, co. Cork ; coast of Cornwall, Mr. Peach f. 



This beautiful little zoophyte measures about half an inch 

 across the tentacular disc, which, as well as the body, is of a 

 bright grass-green, with the exception of a circle of radiating 

 brown striae which surround the mouth at a short distance from 

 its margin. The tentacula are short, the stems of a siena colour, 

 and the capitate extremities of a bright rose colour. Those ten- 

 tacula which lie near the margin of the disc are arranged in two 

 regular concentric circles, and are succeeded towards the mouth 

 by others which are for the most part smaller and present a more 

 scattered disposition. 



There is a variety by no means uncommon, in which the green 

 colour, except in a narrow ring at the upper margin of the body, 

 is entirely replaced by a light flesh colour. In this variety the 

 animal becomes so translucent, that the septa and vermiform fila- 

 ments may often be distinguished through the integuments ; it 

 is an evident example of albinism. 



* From KopvvT], a club, and aKTis, a ray. 



f At the Camhridge Meeting of the British Association in June 1845, 

 Mr. Peach exhibited drawings of a Zoophyte found by him on the Cornish 

 coast, and undoubtedly referable to the species here described. 



