THE CAMPANULABID^ AND THE BONNEVIELLIDjE. 



11 



tentacles and dividing the cavity into two well-defined chambers, the proboscidial and gastric 

 chambers which may have distinct functions, as the histological character of their endoderm 

 would seem to indicate, those of the gastric cavity proper being much larger and with distinctly 

 larger nuclei than those linmg the proboscidial cavity, as shown in fig. 47, taken from Kiilm's 

 excellent paper.' 



In the retracted hydranth the proboscidial cavity is reduced to almost nothing, but in full 

 expansion it is a cavity of considerable size. This same figure shows how the hydranth is 

 anchored to the diaphragm on which it rests by extensions of the stutzlamelle. 



The only other hydroid family whose hydranths have a trumpet-shaped proboscis is the 

 Eudendridse, a gymnoblastic group. It is the opinion of the writer that the characters of the 



HTDKANTHS ( 



' THE CAMPANTJLAEID^. 



Fig. 45. — Campanularia amphora. Hydranth partly expanded. 

 Fig. 46. — Campanularia flezuosa . ( From Ihong specimen. ) 



Fig. 47. — Campanularia flexuosa. (After Kiihn) showing histological details of a young hydranth. 6, gastric cavity, 

 proboscidial cavity, v, Glutinous connection between the " Stutzlamelle " and the diaphragm. 



nJc, Lining of the 



hydranth are of prime importance in the classification of this order, and that there is doubtless 

 a relationship, either of community of descent or of direct descent the one from the other, 

 between the Eudendridse and the Campanularidee. In such a form as Eudendrium vaginatum 

 Allman, in which the perisarc of the stem is extended upward over the proximal part of the 

 hydranth body, we see what might possibly be an incipient hydrotheca of the Campanularian 

 type. ' 



GONOSOME. 



The gonangia bear a general resemblance to those of the Sertularidse, although they are not 

 so varied m form as in the latter family. None of them are ornamented with longitudinal ribs, 

 as in TJiuiaria costata Nutting, and none of them are armed with spine-like processes, as in 

 DipTuisia tamarislca Linnseus. Nor are there any species exhibiting the complicated "marsupial 

 chamber," as found in DipTiasia rosacea. 



' Sprosawachstum und Polypenknospung bei den Thecophoren, 1909, pi. 17, fig. 7. 



