132 



The Caxadiax Field-Naturalist 



Vol. XXXV 



A FAIRY-SHRIMP NEW TO CANADA AND WESTERN NORTH AMERICA 



By Frits Johansen. 



Siuee my article on Canadian and Alas- 

 kan fairy-shrimps was published in the 

 Canadian Field Naturalist, February, 

 1921, I have had the great pleasure of 

 receiving from Mr. and Mrs. T. L. Thaeker, 

 of Little Mountain, Hope, B.C., records 

 that t/hey have kept of fairy-shrimps ob- 

 served and collected in Southern British 

 Columbia, together with samples of the 

 specimens. They prove to be the well- 

 Imown form Euhranchipus vernalis Ver- 

 rill, hitherto not recorded from Canada 

 and the United States west of Indiana. 

 In my article cited above I have mention- 

 ed this species, pp. 24, 27, as one that pos- 

 sesses a wide distribution in the United 

 States, occurring only during the winter 

 and early spring. 



While the genus Streptocephahis (see p. 

 29) was established already by Baird, in 

 1854, the genus Euhranchipus does not 

 occur outside of North America, and was 

 founded by Verrill, in 1869, in describing 

 E. vervalis for the first time. 



Mr. Thaeker 's records of E. vernalis 

 from British Columbia follow: 

 Hope, B.C. : Sloughs in orchard at Little 

 Mountain, through hole in ice, March- 

 April, 1918 (plentiful March 10 and 

 April 1 ; only one specimen March 

 13, 24, and April 21, 28). None se- 

 cured by fishing there on May 26 and 

 June 26, 1918. 



Same place, in 1920 : none secured on 

 Jan. 18 and Feb. 17; one young on 

 Feb. 22. 



Slougli at Haig, Feb. 11, 1920; plenti- 

 ful. 

 Craigdorroch Gardens, Victoria, Van- 

 couver Island : few females with egg- 

 bags in pond, Feb. 14, 1920. 

 According to Verrill and Packard this 

 species reaches a length of 23 mm. in both 

 sexes; and in life the body is of a pale 

 flesh colour, with a deep, reddish-brown 

 colour as a narrow streak widening from 

 the genital organs to the posterior half of 

 the abdomen. The hairs upon the cerco- 

 pods are white, as are also the tips (en- 

 ditesj of tllie basal part of the foliaceous 

 legs. These red-brown and white colours 

 are the most conspicuous ones when the 

 animal is seen in the water. 



The female is easily distinguished from 

 that of E. gelidus (see p. 28), by not hav- 

 ing the ninth and tenth body-segments 

 produced into lateral processes, though 

 the egg-sac is similar, not so long as broad. 

 The male is also easily distinguished from 

 that of E. gelidus by Ihaving the frontal 

 (accessory) organs much shorter, broader, 

 and flatter, triangular in shape and acute- 

 ly pointed, with the edge fineh' serrated. 

 Except when in use they are hidden by the 

 much longer claspers (2nd pair of an- 

 tennae), which have a stout basal joint 

 and a chitinous terminal joint resembling 

 a Turkish sword, with a long obtuse spur 

 on the inner side, basally, beyond whidh 

 the joint is triangular, with the extremity 

 bent outAvard somewhat like the foot of 

 a sock before it is worn. These specific 

 characteristics are illustrated in Pack- 

 ard's monograph (1883), Plates XI, XXII. 



The nauplii (no figures given) were 

 successfully hatched by the two brothers 

 Hay (Anier. Natural.^ Vol. 23, 1889, p. 

 91), (1), from egg-bearing females secur- 

 ed in April, that soon died. The eggs were 

 kept in the dry mud all summer; and 

 when at the end of September they were 

 covered with water, they immediately rose 

 to the surface, remained there for a couple 

 nf days, and then again sank to the bot- 

 tom. In the beginning of October a num- 

 ber of nauplii came forth; they were 

 paler and more transparent than is gen- 

 erally the case with nauplii of fairy- 

 shrimps. Also they seemed to leave the 

 egg in a more advanced stage as a "meta- 

 nauplius" than other fairy-shrimps (there 

 were traces of the first 3-4 pairs of folia- 

 ceous legs, and of the paired eyes), thus 

 recalling the just hatched Lepidurus (see 

 p. 45). 



This species was first recorded by Gould 

 (Rep. on Invertehr. of Mass., Cambridge, 

 1841), who states (p. 339) that they are 

 found in stagnant pools in Massachusetts, 

 but wrongly referred them to the Euro- 

 pean species Branchipus stagnalis L. Ver- 

 rill (Froc. Am. Ass. Ad}K Sc, 1869^ was 

 the first to call attention to this, describ- 

 ing it as E. vernalis and recording it in ad- 

 dition from Connecticut. It has later 

 been found also in Rhode Island, Long 



