NORTHUMBERLAND AND DURHAM. 229 
linear, and placed in a single verticil, as in the present section of 
the family, lately included under Hudendrium, the form of the 
mouth and the power of retraction of the polype within the 
tubular polypary, may be taken into consideration, as well as 
the character of the polypary itself. In Hudendrium, as now 
restricted, the polypes are non-retractile, and have a broad 
trumpet-shaped mouth. In the Atractylis of Dr. Wright, the 
polypes are retractile, and have a conical mouth. The polype in 
Dicoryne has also a conical mouth, but is non-retractile. Upon 
these characters, therefore, I should be inclined to found this 
genus; and it becomes a question whether other genera lately 
proposed ought not to be included in it; as, for instance, the 
Corymbogonium, proposed by Professor Allman, for my Huden- 
drium capillare, which I believe to have a non-retractile polype 
with a conical mouth; and the Garveia of Dr. Wright, in which 
the same characters are found. ‘These genera can only be kept 
apart from the circumstance of some diversity in the gonophores 
or their products. But even in the gonophores the discrepancy 
is not great. The reproductive organs in Corymbogonium are 
produced at the ends of separate branches, and also arise from 
the creeping base. In this they agree with those of Dicoryne, 
but they differ from that genus in their bilocular character, and 
in the absence of the central prolongation (gonoblastidia of 
Allman), which homologically is considered to represent a polype 
destitute of tentacles and mouth. Professor Allman, however, 
very correctly remarks that the enlarged basis, to which these 
gonophores are attached in Corymbogonium, is manifestly the re- 
presentation of a polype, and corresponds to the gonoblastidia of 
Dicoryne. It is also worthy of remark that moniliform gono- 
phores, exactly similar to those of Corymbogonium, and arising 
from short branches, have been found by Dr. Wright on a true 
Eudendrium, his E. arbuscula, and that the E. rameum has also 
moniliform gonophores, but in a different position, being in this 
instance placed below the tentacles of the polype. The gono- 
phores of Garveia nutans, Wright (ELudendrium bacciferum, 
Allman), though produced only singly, also terminate arrested 
lateral branches. I am disposed, therefore; to consider these 
