74 Rev. T. R. R. Stebbing on the Oenus Buthyporeia. 



X. — On the Oenus Bathjporeia. 

 Bj the Rev. Thomas R. R. tSxEBUiNO, M.A. 



[Plate ni.] 



To Lindstrom's original species, Bathyporeia pilosa^ two 

 other species, Rohertsoni and pelagica, have been added bj 

 Mr. Spence Bate. Of the hist, liowever, he had seen but a 

 single imperfect specimen, and none but dead imperfect speci- 

 mens of the other two. As I have been more tortunate, and 

 have been able to examine perfect and living specimens of 

 tliese beautiful little creatures, I have no hesitation in re- 

 ducing all three forms to a single species, the original Buthy- 

 poreia pilosa. There can scarcely be a doubt that what has 

 been figured as B. pilosa is the female, that B. pelagica is its 

 male, and that B. Rohertsoni is also the male not yet arrived 

 at maturity. 



I have taken all three forms on, or rather in, the sands 

 at Llanfairfechan. One specimen of the male I took at low 

 tide near Bangor, one of the female at Pwllheli ; so that the 

 species is probably to be found all round the coast of North 

 AVales. It burrows in the sand to the depth of half an inch 

 or a little more, and exhibits very great activity in this pro- 

 ceeding. When in water it is equally vivacious, darting about 

 in all directions. 



The eyes are faceted, red, and in the mature animal large 

 and kidney-shaped, but small and round in the young. The 

 eyes increase by addition to the number of facets — a mode of 

 growth well known in regard to these organs in the Aniphi- 

 poda, and only requiring notice here because the eyes are 

 given as round in the figure and description of Bathyporeia 

 Rohertsoni. 



The upper antennas do not supply, as was supposed, a mark 

 of distinction between the form given as B, pelagica and the 

 other two, since in all alike the secondary appendage to the 

 flagellum has one large articulus follow^ed by a very slender 

 small one. They are also alike in other respects, and notably 

 in the shape of the large first joint, which stands boldly out 

 in a line with the head, but forms a considerable angle with 

 the two following joints, very diminutive by comparison, and 

 attached to an excavation some little way from its compressed 

 distal extremity. 



The lower antennae do undoubtedly differ in the three forms ; 

 and it is upon these organs that most stress has been laid in 

 distinguishing the supposed species. The principal difference, 

 however, is in the length of the flagellum, which is very short 



