132 THE ROYAL SOCIETY OF CANADA 



neck of Lar. The one tentacle comes out almost at right angles 

 to the body but except for the basal portion no definite position can 

 be given for it as it contracts and expands readily and moves about 

 freely; when extended it is longer than the body, about 1 mm.; the 

 surface is well provided with thread cells but these are scattered 

 singly over the whole length. 



Gonosome. — The medusa-buds grow from the stolon, supported 

 on a very short pedicel. The number of buds in any one colony seems 

 to be rather limited, never more than four in any of the colonies 

 obtained, two being the usual number. But one medusa is produced 

 from each gonophore; it is almost globular, with four radial canals. 



Color. — Main portion of the body and proboscis dirty brown, 

 tentacles transparent. 



Distribution. — On small bivalve shells that appear in large num- 

 bers in muddy bottom in Nanoose bay, at a depth of 10-15 fathoms. 



This unique and interesting species has been found at various 

 points in the Arctic regions from Spitzbergen and the White sea to 

 Greenland and Stafford has reported it otï Gaspe but hitherto it has 

 not been recorded from the Pacific. All the specimens have been 

 obtained by dredging*in muddy bottom at 10-15 fathoms in Nanoose 

 bay. In material obtained on June 21 there were a number of small 

 bivalves on some of which Dr. Mortensen noticed a brownish growth 

 which proved to be the hydroid in question. The colonies at that 

 time had no gonosome present but in dredging over the same ground 

 on August 26 and again on September 22 much material that made up 

 the shortage was obtained so that the development of the medusa 

 could be followed through the early stages. The molluscs to which 

 the hydroids were attached belong to the species Axinopsis sericatus 

 (Carpenter) for the diagnosis of which I wish to thank Dr. C. F. 

 Newcombe. They are quite small, most of them but little more than 

 2 mm. in diameter. A large percentage of the whole number of live 

 shells collected had hydroid growth. In the last instance, out of 346 

 living shells picked from the dredged material, 142 had hydroid 

 colonies attached. The hinge margin serves for the attachm.ent of the 

 hydroids but the stoloniferous network passes across the surface of 

 the shell. The species of mollusc on which the hydroid is found in 

 this locality is not the same as that on which it is found elsewhere. 



When Mereschkowsky first described Monohrachium parasiliim 

 he placed it in a new family Monobrachiidœ and some authors since 

 have followed his example. To me it would seem preferable to place 

 it in the family Laridœ, as Levinsen has done. Anyone who has seen 

 live specimens of Monohrachium could not fail to notice the resemblance 



