90 PKOCEEDINOS OF THE ACADEMY OF [1894. 



TANAIS ROBUSTUS, A NEW SPECIES OF ANISOPODA. 

 BY H. F. MOORE. 



In August, 1892, the collectors of the Marine Biological Labora- 

 tory of the University of Pennsylvania, at Sea Isle City, N. J., 

 brouglit in a large logger-head turtle, ThalassocJielys caretta. 



Examination showed its carapace to be burdened with a miscel- 

 laneous collection of invertebrata, including Polyzoa, Anellida, Cir- 

 ripedea, Pycuogouidia, Caprellidae and a single species of Anisopoda. 



The latter, which has apparently heretofore escaped notice, was 

 found in numbers inhabitincj minute tubes in the crevices between 

 the scales of the turtle's carapace. When unmolested, these little 

 crustaceans could be seen crawling carefully about among their fel- 

 low voyagers or lying at the mouths of their domiciles with only the 

 head and chelae projecting ; when disturbed they promptly retreated 

 out of sight. I am unaware of any other species of the family 

 Tanaidaj occupying a similar position. 



Though differing in some slight particulars from the genus Taiiais 

 as re-constituted by Sars, the sum of its characters evidently places it 

 in that genus and I propose for it the name Tanais robmtus. 



It is quite robust for the family, being less than 3^ times as long as 

 broad. The carapace, which is the broadest portion of the body, is 

 terminated anteriorly by a minute rostrum, whilst its posterior border 

 is somewhat concave in the middle line. In front of the origin of 

 the great gnathopods the lateral outline is strongly concave, but op- 

 posite the bases of these limbs it becomes swollen. When viewed 

 dorsal ly, the carapace appears, in general figure, top-shaped. Two 

 grooves, one on each side, indicate upon the dorsal surface the inner 

 boundary of the branchial chamber. Behind the carapace the 

 breadth of the body becomes gradually less with each successive seg- 

 ment. The fourth free segment of the perieon is the longest, slightly 

 exceeding the third, which is in turn longer than the fifth. 



The pleon is composed of six distinct segments, of which the fourth 

 and fifth are much shorter than the others and the sixth is terminated, 

 posteriorly, by a blunt median projection. The body is constricted 

 at the joints and the segmentation is distinctly marked. The dorsal 

 surface is furnished, laterally, with a few setie, which on the first and 



