[fraser] MONOBRACHIUM PARASITUM 133 



to the attitudes figured and described by Gosse^ and later by Hincks^ 

 for Lar sabellarum. The most striking resemblance is in the continued 

 movements of the body of the zooid and of the tentacle so that a great 

 variety of postures is assumed. The stoloniferous network is similar 

 in the two species and both produce medusa? somewhat similar in 

 shape. The differences are well marked but not sufficiently so as to 

 require a new family for Monobrachium. There are two tentacles 

 in Lar to one in Monobrachium and in the latter there is no constriction 

 corresponding to the neck in Lar, the mouth is terminal not lateral, 

 the thread cells are arranged differently, the medusa buds are not 

 borne in the same manner and, perhaps the most important of all, 

 there are but four radial canals in the medusae instead of six as in Lar. 

 If it were not for this difference in the medusae it would scarcely be 

 necessary even to put it in a new genus. Bonnevie has shown that 

 the gonads of the Monobrachium medusae are placed along the radial 

 canals. Hincks, the only one who has described the medusa of Lar, 

 apparently did not find any medusae far enough advanced to have 

 gonads developed, hence we have no information as to their position. 

 If the gonads are placed similarly to those of Monobrachium, the two 

 genera should certainly be placed in the same family and hence until 

 this question is settled there is no necessity of separating them. 



OBELIA DUBIA Nutting 



Fig. 2 



Obelia dubia nutting, Harriman Hydroids, 1901, p. 174. 



Obelia dubia fraser, Hydroids of Vancouver Island Region, 1914, 



p. 151. 



In giving the original description of this species Nutting mentions 

 three-quarters of an inch as the height of the colony and I found that 

 to be the maximum for all earlier specimens. 



On June 15, a campanularian colony, which had the appearance 

 of Obelia dubia, was obtained in some material dredged in about 25 

 fathoms, from rocky bottom, near Entrance reef, Nanoose bay, but 

 as it was two inches high it did not agree in size with the known speci- 

 mens of that species. There were no gonangia on the specimen but 

 the hydrothecae, with the pedicels and mode of arrangement, resembled 

 those of 0. dubia so much that it can scarcely be doubted that it is 

 this species which was here represented. The unusual length of the 

 colony seems worth recording. 



iGosse, P. H., Trans. Linn. Soc, 1857, p 113-116. 

 2 Hincks, T. British Hydroid Zoophytes, 1868, p. 35. 



On the Hydroid Lar sabellarum, 1872, p. 317-319. 



