NATURAL SCIENCES OP PHILADELPHIA. 165 



tacean from Salt Lake, Utah, caught on the 22d of June by Mr. 

 C. Carrington, a member of Prof. Hayden's exploring party now 

 in the field. They were received from Prof. Hayden with the 

 remark " that Salt Lake has been supposed, like the Dead Sea, to 

 be devoid of life, but its saltest water contains the most of these 

 little creatures." 



The crustacean is the Artemia salina which has long been 

 known in Europe, and has been previously found in other localities 

 of this country. The animal has always been viewed with especial 

 interest, in its order, from the fact that it lives and thrives best in 

 a concentrated solution of salt, which would destroy most marine 

 animals. It has not, I believe, been noticed in the ocean, but is 

 found in salt lakes, and salt vats, in which by evaporation the 

 brine has become more concentrated than sea water. 



Artemia is furnished with eleven pairs of limbs, which serve 

 both for progression and respiration. The limbs are four jointed, 

 and the joints have leaf-like expansions fringed with long feather- 

 like bristles. The narrow abdomen or tail-like prolongation of 

 the body is six-jointed, and traversed by the intestine. The last 

 joint ends in a pair of processes furnished each with a bunch of 

 bristles like those of the limbs. The head exhibits a median, 

 quadrate, black eye-spot, and in addition is provided with a pair 

 of pedunculate, globular compound eyes. A short narrow pair of 

 inarticulate antennas project in advance of the eyes. 



The head of the male is furnished with a pair of singular organs 

 for seizing the female. These claspers are large double-jointed 

 hooks. In the female they are replaced by a pair of comparatively 

 small horn-like processes. The first abdominal segment bears the 

 ovarian sac in the female ; and two cylindroid appendages in the 

 male. 



The female of the Salt Lake Artemia ranges from 4 to "7 lines in 

 length ; the male from 3 to 4 lines in length. The color is trans- 

 lucent-white and ochreous-yellow, with three black eye-spots, and 

 a longitudinal line varying in hue with the contents of the intes- 

 tine. The ovarian sac appears orange-colored from the eggs 

 within. 



The antennas end in three or four minute setas, and are consider- 

 ably longer in the male than the female. The first joint of the 

 claspers is provided on its inner side just below the middle with 

 a spheroidal knob. The last joint forms a rectangular hook, the 

 angle having an elbow-like prominence. When the clasper is 

 thrown forward, the outer border of the hook is convex ; the 

 anterior border straight, slightly, or deeply concave, and the inner 

 or posterior border is sigmoid. The antennas are longer than in 

 the female, and longer than the first joint of the claspers; and in 

 the female are longer than their homologues. The ovarian sac is 

 inverted flask-shaped, and has a pair of lateral conical or lnani- 

 millary, finely tuberculated processes. The caudal setas are longer 

 than in the male, and are eight to each process. 



