HYDROIDS FROM NOVA SCOTIA 169 



himself, in his paper on Arctic Hydro-ids 1 mentions a species 

 that he takes to be the same but he is not sure as he did not 

 find the gonosome. Later Kramp 2 for the same reason could 

 not be sure of the specimens he found. All of these specimens 

 were found in the Arctic or Subarctic regions. There was not 

 such trouble in the case of the specimens found at Canso as the 

 gonophores were numerous. When they are present they are 

 so large and conspicuous that they must be observed before 

 the trophosome is. The trophosome bears so much resemblance 

 to that of H. tenellum that they are hard to distinguish from 

 each other. When the gonosome is present such a mistake 

 could not be made as the gonangium of H. minutum may be 

 as much as 3 mm. in long diameter and not far from that in 

 short diameter. The thickness is not so great, so that alto- 

 gether its shape somewhat resembles the shell of a bivalve. 

 The arrangement of the teeth or spines around the margin at 

 the distal end gives it a unique appearance among the gonangia 

 of the Halecidse. The gonangium of H. muricatum most nearly 

 resembles it, but is not more than one-fourth of the size and 

 it is spiny on the flat surfaces as well as on the margin; while 

 that of H. minutum has but few spines on the margin and none 

 on the flat surfaces. 



The figures show the relatively small stem and the very 

 large gonangium. 



Halecium muricatum (Ellis and Solander). 



Sertularia muricatum E. and S., Nat. Hist. Zooph., 1786, p. 59. 



Halecium muricatum Hincks, British Hydroid Zoophytes, 

 1868, p. 223. 



Halecium muricatum Whiteaves, Marine Invert. Eastern 

 Can., 1901, p. 25. 



On ascidian stalks from 50 fathoms on the Canso Banks. 

 A few specimens, well supplied with gonangia, were collected. 



Halecium tenellum Hincks. 



Halecium tenellum Hincks, Ann. and Mag. Nat. Hist., 3rd 

 ser. VIII, 1861, p. 252. 



J Die Hydroiden der Arktischen Meere, 1909, p. 153 



2 Report on the Hydroids of the Denmark Expedition, 1911, p. 370. 



24853—111 



