MARINE ISOPODA OF NEW ENGLAND, ETC. 323 



Specimens examined. 



Janira spinosa Harger. 



Janira spinosa Harger, Proc. U. S. Nat. Mus., 1879, vol, ii. p. 158, 1879. 



This species is well marked among our known Isopoda, by the double 

 row of si)ines along the back and the acute laciniations or angulations 

 on the lateral margins of the thoracic segments. 



The body is robust, the length but little exceeding twice the breadth. 

 The head is broad, and produced in the median line into a prominent 

 acute spine, or rostrum, about as long as the head. The antero-lateral 

 angles are also produced and very acute, but do not extend as far as the 

 rostrum. The eyes are rounded semi-oval, with the long axes converg- 

 ing toward a point near the base of the rostrum. The basal segment of 

 the antennulse is less than one-third the length of the rostrum. The 

 second segment is about as long as the first, but of only about half its 

 diameter. The flagellum equals, or slightly surpasses, the third antennal 

 segment, and consists of about twelve segments. The scale, or spine, on 

 the second segment of the antennae is .slender and considerably surpasses 

 the third segment. The external lamella of the maxillipeds has the 

 outer angle prominent, though not acute. 



The thoracic segments are produced laterally into one or two acute 

 angulations, giving a sharply serrated or dentated outline to the tho 



