January, 1921] 



The Canadian Field-Naturalist. 



5 



trally placed low mound about 60 cm. in 

 diameter and 5 cm. high. In the centre of 

 this mound was a broad funnel-shaped de- 

 pression leading into the main entrance of 

 the system of burrows. Scattered for some 

 distance around the mound, within a circle 

 with a radius of from three to five feet or 

 even more, and opening from the burrows, 

 were a number of holes of the same dia- 

 meter, their margins being flush witli the 

 surface of the mud. One system was 

 traced out by opening up all the burrows. 

 It is represented in figure 2. It will be 

 seen that this system is not very regular, 

 and shows a development of the burrows 

 almost wholly on one side of the mound. 

 Most of the branches open to the surface, 

 but some end blindly. The openings are 

 to be found not onlv at the ends of the 



the laboratory, in a flat, Shallow tank pro- 

 vided with running salt water. They were 

 heard making a very considerable com- 

 motion in the late afternoon and evening, 

 and on the next morning one was found 

 dead on the floor. On the following morn- 

 ing another was found dead. Boards were 

 then fastened around the edge of the tank, 

 and the remaining fish was kept without 

 difficulty through the season. 



This individual, which was about 45 

 cm. in length, was a male, judging from 

 the examination made of the others. On 

 June 24th, a piece of black, hard rubber 

 pipe, 17s inches outside diameter, 1% 

 inches inside diameter, and 8 inches long, 

 was placed in the tank. After a time the 

 fish entered the pipe and took up a rest- 

 ing position with botli- ends protruding, 



Fig. 3. Wrymouth reclining in a tube in the aquarium. 



photograpia (A.G.H.). 



Sketched from a 



branches, but also at the junctions and 

 along the course of the branches. 



The fish were found to emerge, not from 

 the main opening in tlie mound, but from 

 one of the other openings, which sliows that 

 they were pointing aAvay from the mound. 

 We suppose that the mound opening is the 

 point from which the Ijurrows were form- 

 ed, that the mode of formation was the 

 thrusting of the animal "s head through the 

 soft mud, and that the other openings are 

 necessary for the indraught of fresh water 

 in breathing. Its method of bringing 

 fresh water into its burrow, to be des- 

 cribed later, is such as to cause a current 

 to flow from the peripheral openings to- 

 ward the centrally placed entrance, and 

 from this current is doubtless deposited 

 the material that forms the mound. 



Three of the wrymouths were placed in 



but with more of the head than of the tail 

 exposed (Figure 3). Later the head was 

 drawn back until just concealed. The pipe 

 rolled somewhat when the fish moved, and 

 finally the fish left the pipe. The latter 

 Avas then steadied with stones, and, when 

 the fish again entered, it Avas not readily 

 abandoned. 



Locomotion. Forward movements were 

 accomplished by means of undulator}- lat- 

 eral motions of the tail and posterior part 

 of the trunk well forward to the head, the 

 dorsal fin of that part being kept erect. 

 Backward movements were accomplished 

 by pressing the tail or part of the trunk 

 forward against objects, and by placing; 

 the pectoral fins on the bottom and turn- 

 ing them forwards. In forward and back- 

 ward movements the median (dorsal and 

 anal) fins were kept flexed except as men- 



