ISOPODS OF NORTH AMERICA. 635 



'' The first two segments of the pleon have their lateral processes, 

 or coxae, obsolete, as usual in the family, but the third, fourth, and 

 fifth segments are produced laterally into broad plates, which are close 

 together and at their extremities continue the regular oval outline of 

 the body with scarcely a perceptible break between the thorax and the 

 pleon. This outline is further continued by the expanded basal seg- 

 ment of the uropods, which are even larger than the adjacent coxae of 

 the fifth segment. At the extremity of the pleon both pairs of rami 

 are visible, the inner springing from near the base of the basal seg- 

 ments below, the outer from a notch near the middle of the inner 

 margin of the basal segment. The rami are tipped with setae, and the 

 inner just surpass the outer, which in turn surpass the produced por- 

 tion of the basal segments. 



"Length, 4 mm.; breadth, 2 mm. ; color in life, slaty gray."- 

 OSCAR HARGER." 



ACTONISCUS LINDAHLI, new species. 



Body oblong-oval, a little more than twice as long as wide, 2 mm. : 4i 

 mm. Surface of body distinctly covered with low tubercles. 



Head with the anterior margin produced in three long lobes, the 

 median one having the dorsal surface concave and being produced as 

 far as the lateral lobes. All three lobes have the anterior extremities 

 truncate. The eyes are small, composite, and placed at the base of 

 the lateral lobes. The first pair of antennae are small and inconspicu- 

 ous. The second pair have the first article short; the second is about 

 twice as long as the first; the third is equal in length to the second; 

 the fourth and fifth are subequal and each is about one and a half times 

 longer than the third. The nagellum is composed of four articles, of 

 which the second is the longest. 



The segments of the thorax are subequal. The post-lateral angles 

 of the first segment are produced backward in acute processes. The 

 antero-lateral angles of this segment are also somewhat produced to 

 surround the head. The epimera are not distinctly separated on any 

 of the segments. 



All six segments of the abdomen are distinct. The first two have 

 the lateral parts covered by the seventh thoracic segment. The lateral 

 parts of the third, fourth, and fifth segments are expanded so as to 

 continue the oval outline of the body. The sixth or terminal segment 

 is triangular in shape, with apex acute. The basal article or peduncle 

 of the uropoda is large and expanded and simulates the lateral parts 

 of the fifth abdominal segment. The outer branch is inserted at the 

 inner margin of the basal article about halfway between the base and 

 the extremit} 7 ; it does not extend beyond the posterior margin of 

 the basal article. The inner branch is inserted at the upper inner 



"Report U. S. Fish Comm., 1880, Pt. 6, pp. 309-310. 



