﻿114 



PROCEEDINGS OF THE 



[April, 1857. 



found with their small lateral tentacula, but with no ordinary- 

 lash. (PI. 12, fig. 2.) Again, in the whole Tubularian group, 

 we have not a single instance, at any age of the animal, of those 

 remarkable sense-capsules, under the form of little pendent, trans- 

 parent vesicles, containingcorpuscles which sometimes appear to be 

 inorganic concretions, while these are characteristic of nearly all 

 the genera of the Sertularian group, including the Aeginidse. In 

 fact, ocellary pigment spots, which are characteristic of most 

 genera among the Tubularina, are to be found only in Thau- 

 mantias,* Tiaropsis, and Staurophora, among the Sertularina, 

 and their absence in the rest is supplied by the presence of sense- 

 capsules. And I suggest the probability, from analogy, of Thau- 

 mantias and Tiaropsis, with Eucope, that these ocellated species 

 will be found characterized by such marginal capsules in the 

 early stages of their existence, for those organs are observed in 

 Eucope and Cunina in the earliest stages of their Medusa form, 

 while nothing like them are seen at any stage of existence in such 

 genera belonging to the group of Tubularina, as have been ob- 

 served. 



There are two facts which appear to militate against this separa- 

 tion of Tubularina from Sertularina — the first that Eudendrium 

 ramosum described by Van Beneden, appears to be an intermedi- 

 ate form between them. This genus produces free medusas 

 (which there is very strong reason to believe are Hippocrenidse) 

 after the ordinary Tubularian manner, but has, according to Van 

 Beneden, some terminal enlargements of the branches very 'simi- 

 lar in appearance to the medusa-bearing capsules of Sertularians. 

 thus leading to the impression that it may possess both modes of 

 developing Medusae. But certainly there are no observations to 

 countenance this view, and it is very probable that Van Beneden 

 was right in his conjecture that the enlargements referred to were 

 produced by some parasite within the tube, or it is even quite pos- 

 sible that this may be the form which a creeping branch takes 

 before it has fixed itself and begun giving rise to polyps. See 

 below Hippocrene and Eudendrium. 



Next, it may be thought that the mode of growth exhibited by 

 the radiate tubes in the Tubularian method, renders the reality of 



*It is evident that Forbes made no constant distinction between well defined 

 ocellary spots and the mere coloration of the tentacular bulbs which often exists 

 without the presence of ocelli. The greater ocellus in Tiaropsis, however, is 

 perhaps a combination of the ocellus and the concretionary capsule. 



