EUDENDRIUM RAMOSUM. 333 



designation by wliicli the descriptive phrase of Ellis was superseded in the ' Systema Naturse.' 

 It is consequently a very diiferent hydroid from the Etidcndrium ramomm of Van Bencden. 



It was first described and figured by Ellis from specimens obtained upon the coast of Kent, 

 but without any reference to the gonosome, an omission which may be explained by the fact tliat 

 Ellis's specimens had been gathered in August, and therefore after tlie gonophores had dis- 

 appeared. 



The hydrauths, which are of a fine vermilion colour, are very conspicuous even to the naked 

 eye, while the beauty of the male colonics is greatly enhanced by the presence of the gonophores. 

 These are two-chambered and spring in a regular verticil from the body of the hydranth, about 

 half way between the origin of the tentacles and the summit of the supporting branch. 



The hydranth in the male colonies is at first, while it continues to retain its full development, 

 embraced by its circlet of gonophores from whose midst the tentacles rise in a graceful cani- 

 panulate plume. Frequently, however, the hydranth, as if starved by the growing gonophores, 

 and their increasing demand for nutrition, becomes atrophied, the tentacles entirely disap[)ear, 

 and the whole becomes changed into a short column, which carries the gonosacs in an umbel on 

 its summit. With the atrophy of the tentacles the mouth seems also to disappear, and the 

 hydranth has thus assumed all the characters of a blastostyle. It is a blastostyle, however, 

 merely from atrophy, and must not be confounded with a true blastostyle, which, though strictly 

 homologous with a hydranth, belongs, from its origin, to a special and independent morphological 

 modification. 



In the female colonies the gonophores are without the synunetrical arrangement so striking 

 in the male, and, instead of being disposed in a regular verticil, are scattered on the body of the 

 hydranth, and on the distal end of the branch. They are of a reddish-orange colour, and 

 increase in maturity as we trace them downwards on the branch. The tentacles of the hydranth 

 are here, also, as in the male, often dwindled ; but I have never met with that complete atrophy 

 which is of such frequent occurrence in the male. 



The perisarc constitutes a firm, elastic, horn-like covering. The hydrocaulus in full-sized 

 specimens is about half a line in thickness towards its base, and here presents a fascicled structure 

 formed by the mutual adhesion of several simple capillary stems. It soon, however, loses this 

 condition, and then continues as a singled branched tube for the rest of its course. The compa- 

 ratively small diameter of the stem, even at that part where the fasciculated condition exists, and 

 the fact that the fasciculation is confined to those parts which are near to the attached end of the 

 hydrosoma, has caused this character to be overlooked in the description given by Ellis, while 

 Pallas ascribes to the species an absence of fasciculation as one of its leading diagnostic charac- 

 ters. This error has doubtless been strengthened by the fact that many of the specimens wdiich 

 have been found entangled in the lines of the fishermen, or otherwise detached from their place 

 of growth, have been so torn away as to leave most or the whole of the fascicled portion behind 

 them. 



