130 



The Canadian Field-Naturalist 



[Vol. XXXIV. 



development of the Cammarus eggs takes place in 

 much shorter time, and are thus not carried for so 

 long a period by the mother-animal compared with 

 Eucrangonyx. The young ones are probably born 

 in May, July and September in the latitude of the 

 Great Lakes. Cammarus limnacus is said to range 

 in the United States from Maine to Utah, and has 

 formerly been recorded from Lakes Superior, Michi- 

 gan and Georgian Bay. It has also (Pearse, 1913) 

 been recorded from lakes in the neighborhood of 

 White Horse, Yukon Territory and Rampart 

 House, Alaska (Porcupine River). I have (be- 

 side the Arctic ones mentioned above) a number of 

 hitherto unpublished records from additional locali- 

 ties, which I give here, arranging them from east 

 to west, 



Observed (animals escaped) in pool at Tadou- 

 sac, P.Q., September 6th, 1919; young individuals. 



Stream-pool between St. Lawrence River and 

 Diamond Hill, Quebec City, September 19, 1919; 

 many specimens (4-9 mm. long.) 



Bight at Alexandra Bay, N.Y. (Thousand 

 Islands), September 1st, 1919; many specimens up 

 to 10 mm. long (females with eggs.) 



I have not yet found this species around Ottawa, 

 though the two smaller freshwater-amphipods, (Eu- 

 crangonyx gracilis, and H^alella knickcrbocfferi) 

 are common here; but Prof. E. M. Walker, of 

 Toronto, has sent me some (Yz doz.) full grown 

 specimens of this species collected near Whitefish 

 Creek, Lake Simcoe, Ont., on June 17, 1917. 



From Manitoba I have before me ten specimens, 

 full grown, about (2 cm. long) collected by E. 

 Criddle, at Treesbank,(Assiniboine River), Novem- 

 ber 21, 1917; and two specimens (1 smaller, one 

 almost full grown), from Cross Lake (about lat. 

 54 !/2 N.) collected by F. J. Alcock in the sum- 

 mer of 1919. 



I have no records of this species from Saskatche- 

 wan, though it undoubtedly occurs there, having 

 been found both in Manitoba and in Alberta. 



From Alberta I have before me twenty-seven 

 specimens, about 2 cm. long, from Dodds Lake, 

 near Edmonton, collected by a university student 

 there on March 8, 1919 and sent to me by Dr. Mc- 

 Lean Eraser of Nanaimo, B.C. 



Also Yz dozen specimens from Miquelon Lake, 

 Alberta (about lat. 53 N.), collected on Septem- 

 ber 30, 1918, by R. M. Anderson, of Ottawa. 



Many specimens (mostly full grown) from a 

 marsh in Cabin Lake Creek, Jasper Park, col- 

 lected by W. Spreadborough, on Aug. 31, 1918. 



Also 1 Yl doz. specimens from the plain near 

 Red Deer and Battle Rivers, east of the foot- 

 hills. Alberta (about lat. 53 N.) collected by 

 J. B. Tyrrell, June to September, 1885. 



From British Columbia I have examined the fol- 



lowing specimens: 



Three large ones from Sink Lake, near Stephen, 

 E. Kootenay county, B.C., September 26, 1883, J. 

 B. Tyrrell, collecter. 



Half a dozen from Beaver Pond in valley of 

 Kish-e-nek-na creek, (Flathead River, near Inter- 

 national Boundary, B.C.) August 27, 1883, J. B. 

 Tyrrell, collector. 



We now come to the third family of freshwater- 

 amphipods, namely the Orchestiidae, represented by 

 only one species on this continent the common 

 Hyalella (allorchestes) knickcrhoclferi. Bate. The 

 other species (H. azleka Lauss, H. dentata. Smith, 

 H. inermis Smithy described formerly Jiave proved 

 to be only varieties. In addition to the characters 

 given for the family, (p. 128) this amphipod is 

 immediately recognized by the presence of a curved 

 spine projecting backwards from the middle of the 

 posterior margin of each of the first two abdominal 

 segments, a character which can be seen with the 

 aid of a strong magnifying glass, and reminds one 

 strongly of certain marine (especially arctic) am- 

 phipods.* 



The biology of Hyalella f(nickerboc}(eri has been 

 studied by various naturalists and a rather full ac- 

 count of it has been given by H. H. T. Jackson 

 (1912). He says it is a littoral form, only occur- 

 ring to the depth of about one fathom of water in 

 larger lakes, and that it prefers sluggish streams 

 and lakes, etc., with much vegetation. He states 

 that it feeds almost exclusively on protozoa and 

 algae, which it gets by swimming or crawling. He 

 found it was more active at night than during the 

 day time, also that there was much variety in its 

 color, and that the latter was not solely due to 

 food in the intestine (compare Eucrangonyx gracilis, 

 p. 129). The largest specimen he observed was 7.6 

 mm. long; the females average less than the males 

 in length, but are deeper in the body. According to 

 the author quoted, the species breeds throughout the 

 year, but especially during the summer; while thus 

 engaged the male carries the female, though releas- 

 ing his hold when the moulting takes place. Soon 

 after copulation the eggs pass into the ovarial sack 

 (brood-pouch) of the female, but they take almost a 

 month to hatch. Jackson paid particular attention to 

 the moults. He found, that there is a varying period 

 (1 to 5 weeks) between the moultings, and that 

 each moult begins with a transverse split in the fore- 

 part of the body. Contrary to what is the case 

 with many Crustacea (for example the cray fishes) 

 the moulted skins are not eaten by these amphipods 

 after being cast. My own observations on the 

 biology of this animal agree with those of Jackson 

 except that he says it does not occur in temporary /^J 



*Shape of Hyalella is more robust and rounded^^ 

 than Eucrangonyx of corresponding size (see ^-^O 

 129). 



