ORDER ISOPODA — STENOSOMA. 43 



(EXTRA-LIMITAL.) 



I. triloba. (Say, 1. c. Vol. 1, p. 425.) Body oval, somewhat oblong ; its segments with the lateral 

 processes very convex, lobated. Eyes very prominent. Middle lobe of the tail the largest ; the last 

 longer than all the others together, subtriangular. Feet armed with very strong acute incurved 

 nails. Length, 0-25. Egg harbor. 



GENUS STENOSOMA. Leach. 



With the general characters of the preceding. Body sublinear. External antenna? nearly as 

 long as the body, not comprising the tail ; internal antennae very short. Feet robust. 



Obs. This genus has been united by recent authors with the preceding. 



Stenosoma irrorata. 



plate x. fig. 42. 



(state collection.) 



Stenosoma irrorata. S±Y, Jour. Acad. Nat. Sciences, Vol. 1, p. 423. 

 S. id. Gould, Invertebrata of Mass. p. 338. 



Description. Body oblong, somewhat tapering at each extremity, and composed of seven 

 segments ; those in the midde of the body largest ; no appearance of articulation on the sides 

 of the second or following segments. Eyes prominent, brilliant, black and lateral. Tail of 

 four segments ; the three first small, subequal ; the third obsolete above. The fourth or ter- 

 minal segment is nearly as long as four of the body segments, obsoletely carinate on the 

 dorsal surface ; tip with an elongated central point, and an obtuse tooth on each side. Lateral 

 appendices oblong, rounded, with a transverse articulation near the posterior tip. Feet multi- 

 articulate, hispid at the joints with acute incurved claws. External antenna? scarcely exceed- 

 ing in length the ultimate segment of the tail, with a minute spine on the inner side of the 

 tip of the first joint ; but this is not observable except in the largest specimens. Internal 

 antennae very short, scarcely reaching the tip of the third joint of the outer antennae. The 

 last joint of the exterior antennae is composed of more than, twenty articulations. 



Color, varies from deep purple to sea-green and even reddish. Some are of a uniform 

 color, whilst others are varied with light sea-green and cinereous brown. The specimen 

 figured in the plate, represents one with two longitudinal sea-green bands. Scarcely any two 

 individuals are alike in their markings. 



Length, • 2 - 1 • 0. Width, • 03 - • 05. 



6* 



