420 GEOLOGICAL SURVEY OP THE TERRITORIES. 



VI. MISCELLANEOUS NOTES ON THE EEPKODFCTIVL HAB- 

 ITS OP BRANCHI0P0DID.E.1 



By Carl P. Gissler, Ph. D. 



I. EUBRANCHIPUS VBRNALIS Verrill.^ 



Among tlie very large individuals gathered during the past winter 

 (1879-'80), I found a male and female, each with but one right clasper. 

 Several experiments on Eubrauchipus showed that the least artificially 

 applied lesion of the clasi)ers proved to be fatal to them, and so I am 

 inclined to see in the above mentioned two specimens simply a mal- 

 formation acquired through some unknown cause at an early larval 

 stage. Where the other claspers ought to be the integument is perfectly 

 smooth and rounded. During eleven days I could never see the mal- 

 formed male in copulation, although I always noticed him pursuing the 

 females. He was frequently seen to be touched by other normal males, 

 especially when they approached his left side from behind, on account 

 of the missing left clasper, and also probably on account of the exces- 

 sively swollen genital segment, taking it for a fenaale bag. This singu- 

 lar individual presented altogether much oddity in its behavior. Un- 

 like the others, it often swam suddenly through the aquarium in a bee- 

 line, frequently resting on its back at the bottom of the jar for 10 or 12 

 minutes, slowly moving its branchipeds. Perfect sammersaults and 

 other curious motions were often noticed. 



The malforined female did not i)resent any odd movements; I kept it 

 for several days alive and could see no other anomaly about it. The 

 largest females usually preferred the bottom of the aquarium as a 

 protection against the ever- attacking males. In old females I often no- 

 ticed a laceration of the furca^ (sometimes entirely gnawed off), caused 

 by insect-larvae crawling about the bottom. They bear a lacerated 

 furca well for a long time, as the farca merely consists of chitin and 

 bristled integument. 



' The larger i)onds were found already in January to swarm with Lym- 

 netis gouldii Baird, a great number of a species of Daphnia, many Cy- 

 pridinse, Cyclopidse, and Calanidse. 



If the months of November and December are mild, as has been the 

 case during the past three years, there occur in January adults 1^ inches 

 long, as well as larvae of only a few millimeters in length. Three years 

 ago they disappeared in the beginning of May, year before last in April, 

 last year in March, and this year (1881) in the middle of April. A sudden 

 change in temi3erature, warm or cold, will cause them to disappear for 

 two or three days, wben, after another change, they suddenly reappear 

 diminished in number and in comijany with another young generation. 



The female sexual organs of the red Eubranchipus vernalis are less 

 complicated than those of its pale races, and I have occasionally alluded 

 to them in describing those of the latter. 



Copulation in the red Eubrauchipus lasts but a moment, and on this 

 account I was unable to closely observe the same. 



SEXUAL ORGANS. (Plate XXII.) 

 (1.) Male organs. — The posterior (lower) tapering end of the testicle is 

 fastened by a very fine hyaline thread to the wall near the eighth post- 



1 This is in part a continuation of a paper entitled "Evidences of the effect of chem- 

 ico-physieal influences in the evolution of Branchiopod Crustaceans," read before the 

 29th meeting of the Amer. Assoc. Adv. Sc. held at Boston, Aug. 1880. 



2 Observations on Phyllopod Crustacea, ^etc, by Prof. A. E. Vemll, 1869. 



3 The red Eubrauchipus has a white furca, the pale races have a red furca. 



