10 MICHIGAN FISH COMMISSION— BULLETIN NO. 5. 



Genus EPISCHURA Forbes. 



Plate II, fige. 1-6. Plate III, figs. 1-6. 



Epischura lacustris Forbes. 



1844. Scopixtphora vagans Pickering, p. 62. 



1882. E. labustris Forbes, pp. 541 and 648, pi. VIII, figs. 15, 16, 21, 23 y . 



pi. IX, fig. 8. 



1884. E. lacustris Herrick, p. 131, pi. Q, fig. 13. 



1889. " " DeGuerne and Bichard, p. 90, pi. IY, figs. 3, 9 and 10. 



1891. " " Forbes, p. 704, pi. I, figs. 1-5; pi. II, fig. 7. 



1893. " " Marsh, p. 200, pi. IY, fig. 6. 



I have very little doubt that, as stated by Herrick ('84, p. 131), the 

 Scopiophora vagans of Pickering is the same as E. lacustris. The state- 

 ment in regard to the armature of the abdominal furcae can apply to no 

 other genus, and as only one species of Epischura has been found in the 

 Great Lakes, there would seem to be little doubt as to the identity of Pick- 

 ering's species. If then we follow the laws of priority as strictly as do 

 some authors, we should throw out Forbes's name. But I cannot think it 

 wise when a name has been so long incorporated in our literature, and is 

 founded on an accurate and easily recognized description, to throw it aside 

 in favor of a name accompanied by a description which, it is true, probably 

 applies to this animal, but is manifestly inaccurate in some particulars, and 

 may be in all. 



It is not necessary to give a detailed description of this species, as that 

 has already been done by other authors, but, as very few figures of it have 

 been published, it has seemed best to me to draw quite a number in order 

 that they may serve for comparison of this genus with others, and of the 

 various species of Epischura with each other. 



A few points in the anatomy, which have not been noted by others should 

 be mentioned. 



Forbes has recently ('93, p. 255) called attention to the fact that the 

 fourth abdominal segment of the male is without a process, and that the 

 fifth bear? two processes. 



The antennae are 25- join ted. In the female, clavate sensory setae are 

 present on all segments except the 4th, 6th, 8th, 10th, 20th, 21st, 22d and 

 24th. The 8th and 11th segments have each a short spine. The left 

 antenna of the male is like those of the female except that the sensory 

 setae are much longer, particularly on the basal segments. The right 

 antenna of the male is 22-jointed, with a hinge between the 18th and 19th 

 segments. The 19th segment is formed by the union of the 19th, 20th and 

 21st of the typical antenna, and the 20th by the union of the 22d and 23d. 



The outer rami of the swimming feet are three- jointed, and the inner 

 * one- jointed. In all the feet the inner ramus bears five setae. In the first 

 foot the first and second joints of the outer ramus have each one external 

 and one internal seta. The terminal joint has six setae. In the second, 

 third, and fourth feet, the first and second joints of the outer ramus have 

 spines externally instead of setae as in the first foot. The terminal joint 

 has two short spines externally, a long terminal spine with its outer margin 

 deeply serrate, and four setae on the internal margin. 



