368 REPORT—1863. 
developed codonostome and velum, and, the manubrium now becoming per- 
forated by a mouth, the gonophore is no longer dependent on the trophosome 
for its nutrition, but can become free and lead an independent life in the 
open sea (fig. 6 D and fig. 17). 
The typical and ordinary condition of the spadix is that of a hollow cylin- 
drical or clavate body, occupying the axis of the adelocodonic gonophore. 
Occasionally, however, it departs from this condition and becomes more or 
less branched, as in Plumularia pinnata, Laomedea caliculata, &e. 
The gastrovascular canals may, as we have already seen, be either entirely 
suppressed, or present the condition of simple, short, blind tubes, radiating from 
the base of the gonophore, or be continued from this point as fully developed 
radiating canals to the distal extremity of the gonophore, where they become 
united by a circular canal. In Cordylophora lacustris*, however, instead of 
being simple tubes, they consist of irregularly branched and anastomosing 
* The genus Cordylophora was founded by me, in 1843 (Reports of the Meeting of 
the British Association held in Cork, 1843, and Ann. Nat. Hist. xiii. p. 330), for a 
remarkable tubularidan with scattered filiform tentacula, a well-developed periderm, and 
with adelocodonic gonophores scattered-upon the ultimate ramuli of its branching tro- 
phosome,—a tubularidan, moreover, singularly exceptional in its mode of life, being, with 
Hydra, the only known hydroid which is an inhabitant of fresh water. 
Agassiz, in his recent work (Nat. Hist. of the United States, vol. iv. p. 289), refers the 
genus Cordylophora to the genus Syncoryna of Ehrenberg, which he reconstructs for this 
purpose. From such a determination, however, I must altogether dissent. The name 
Syncoryna was introduced by Ehrenberg, in 1832 (Beitriige zur Kenntniss der Corallen- 
thiere des Rothen Meeres), to replace that of Stipula, Sars’s name for a genus of hydroids 
exactly equivalent with the Coryne of Gartner, a genus from which Cordylophora is abso- 
lutely excluded by, among other characters, its filiform tentacula destitute of capitula. 
Ehrenberg thinks that a hydroid discovered by Cavolini in the Bay of Naples, and de- 
scribed by him under the name of Sertularia parasitica (Mem. Polypi Marini, 1785, pl. vi. 
figs. 8-13), belongs to the genus Syncoryna=Stipula. In this, however, he is evidently 
mistaken, Cavolini’s hydroid, so far as we can judge from the account left us by its dis- 
coverer, being altogether excluded from the genus Stzpula as defined and fixed by Sars. 
If Ehrenberg had not been, like Sars, led into error as to the just application of the name 
Coryne, he would, instead of changing Sars’s name of Stipula for one of his own, have 
simply restored the old name of Coryne as originally given by Gartner. 
Agassiz, however, retains the generic name of Syncoryna, Ehr., but modifies the genus 
by removing from it all the forms included in it by Ehrenberg, except the Sertularia pa- 
rasitica of Cavolini, which, as we have just said, was erroneously placed there by Ehren- 
berg. To this he adds the species of the genus Cordylophora, under the belief that Cor- 
dylophora lacustris and Sertularia parasitica ave congeneric forms. 
Even allowing that this reconstruction of Syncoryna in a sense which was not under- 
stood by its founder is admissible, I must entirely differ from Agassiz in his generic asso- 
ciation of Cordylophora with the Sertularia parasitica. 
The Sertularia parasitica, already taken by Van Beneden as the type of a new genus, 
Corydendrium, Van Ben. (Bull. Ac. Brux. 1844), is certainly a very remarkable hydroid, 
and it is greatly to be desired that we knew something more of it than what is to be 
gathered from the figures and description (excellent though they be for the time) which 
have been left us by the celebrated Neapolitan observer. From these, however, so far as 
they go, we learn that it has a curious complex ccenosarc, consisting in the main stems of 
fascicles of tubes which become single only in the smaller branches; that it has a singu- 
larly extensile and dilatable proboscis ; and that, if we be justified in offering any interpre- 
tation of the curious buds represented in one of the figures (fig. 11, c), we must regard 
them as phanerocodonic gonophores, for it is impossible not to recognize in them a close 
resemblance to young medusee still enclosed in the ectotheca. Of the singular formation 
of egg-like bodies in the interior of the stems, as described by Cavolini, I cannot offer any 
explanation. 
In all these points Cavolini’s hydroid stands widely separated from Cordylophora, and 
it cannot therefore be associated with it in a common generic group. 
T must therefore continue to maintain the independence of Cordylophora as a legitimately 
constituted genus. 
