January, 1921] 



The Canadian Field-Naturalist. 



preceded hy a rather prolonged series of 

 masticatory movements involving both 

 mouth and" tliroat, and in which the head 

 was nodded vigorously by movements in 

 the vertical plane, the downward ones being 

 the more vigorous. 



The enormous pectoral fins were used 

 in slow backward and fcrward locomotion, 

 each fin being kept in a vertical position 

 and slightly folded with the convex side 

 in the direction of movement. At rest 

 each fin is held out from the body almost 

 in the lioi'izontal plane and against the 

 bottom, with the dorsal i)art posteriorly 

 placed and somewhat raised. Rapid swim- 



ming is accomplished by undulatory move- 

 ments of the posterior part of the trunk 

 and tail; the pectoral fins being extended 

 to the fullest extent and held horizontally 

 with the dorsal edge in front, while the 

 dorsal and anal fins are kept close to the 

 body, at least anteriorly. 



Touching the side of the trunk or tail 

 resulted in the erection of the dorsal fhi. 

 After repeated stimulation the response 

 became rather local, extending both for- 

 ward and backAvard from tlie level of the 

 point touched, but chiefly backward. At 

 the same time the fin was bent toward the 

 side stimulated. 



THE LlARl) RIVER FLOOD OF .U'LY 191!). 

 By E. J. Whittaker. 



In a recent issue of the (i(o<jr(iphic(il 

 Review- Dr. E. M. Kindle states that the 

 Liard is the main source of supply of drift- 

 wood for tlie Mackenzie River, and that 

 "the unusually high stage which the Liard 

 reached in 1919 set afloat a vast quantity 

 of stranded logs, many of which had start- 

 ed their northern journey in previous 

 years." In view of the fact that this flood 

 was unprecedented within the memories of 

 the present inhabitants of tlie i-egion, and 

 also that the writer was ascending the Liard 

 during the period of maximum flood con- 

 ditions, the following observations are pre- 

 sented which may be of interest to readers 

 of this publication. 



After a quick trip from Edmonton the 

 Geological Survey party to which the 

 Avriter was attached reached Fort Simp- 

 son, N.W.T., on July 1st, 1919. This fort 

 is situated on an island at the junction of 

 the Liard and Mackenzie Rivers, and at no 

 other point is there a more striking view 

 of the width and volume of this northern 

 waterway. Upon enquiry we were told 

 that the flood stage of the river had reach- 

 ed its maximum about three days before, 

 and had now fallen four feet below the 

 high water mark. The following day, 

 Wednesday, July 2, we commenced track- 



1 Published by permission of the Director of 

 the Geological Survey of Canada. 



-Kindle, E. M., "Mackenzie River Drift- 

 wood", Geographical Review, Vol. XI, January, 

 192], No. 1. pp. 50-53. 



ing up tlie Liard. Owing to the high 

 water, travel was not easy, yet we hoped 

 it would steadily improve as the river level 

 lowered. It did actually lower until Sat- 

 urday afternoon, July oth, during which 

 time we re^iched and i)assed the long series 

 of rapids about thirty miles above Fort 

 Simpson. We camped that evening on the 

 shore opposite the lowei" end of Gros Cap 

 Island, at the upper end of the canyon. 

 During the afternoon a slight increase in 

 the quantity of driftwood warned us that 

 the river was once more rising. All day 

 Sunday it rose slowly but steadily, ten 

 inches in the twenty-four hours. 



About midnight of the 6th, the noise of 

 the water and the grinding and breaking 

 of trees increased perceptibly. The river 

 became quickly covered with driftwood 

 from bank to bank and encroached rapidly 

 upon our camp site, which had been se- 

 lected for convenience rather than with an 

 eye to floods. This site had to be abandon- 

 ed. As higli ground was a long distance 

 back through a dense forest and it was 

 now impossible to go upstream against the 

 driftwood laden waters, which were already 

 undermining and dropping trees into the 

 river, we went carefully downstream three 

 miles to Poi)lar river, where a bank 250 ft. 

 high made certain that we could retreat as 

 high as necessary, and the dead water at 

 the mouth of the smaller stream made a 

 secure harbour for the canoe. 



We remained at this camp 4 days, dur- 



