no. 1811. A NEW ISOPOD FROM ARGENTINA— RICHARDSON. 171 



Fig. 4. Chiriscus australis. 

 Second leg. x 20i. 



antennse, and are geniculate at the second article; the first article 

 is short ; the second is twice as long as the first ; the third and fourth 

 are short, about equal in length to each other and to the first article, 

 the fourth having the outer lateral margin produced in a large 

 rounded process or lobe; the fifth article is a little longer than the 

 preceding; the flagellum is composed of eleven articles. The sec- 

 ond antennae are almost entirely concealed in a dorsal view by the 

 first antennas. 



The first, second, and third segments of the thorax are about equal 

 in length in the median line, being each three-fourths mm. long; the 

 fourth, fifth, and seventh segments are a little 

 shorter, being each about one-half mm. in 

 length; the sixth segment is the longest, being 

 1 mm. long. Epimera are present on all the 

 segments except the first; they are visible in a 

 dorsal view only on che last three, being wide 

 and occupying the entire lateral margin ; in the 

 other three segments they are narrow plates 

 and extend only half of the lateral margin. The 

 thorax tapers toward the posterior extremity, 

 which is narrower than the anterior portion. The seventh segment is 

 abruptly narrower than the sixth segment, and is not wider than the 

 first abdominal segment - 



The abdomen is composed of three segments, two short segments 

 anterior to the long terminal segment. The terminal segment is long 



and narrow, 3 mm. by 1J mm., and tapers to 

 a pointed extremity. 



The first pair of legs are strongly prehen- 

 sile, with the propodus large, dilated, and the 

 dactylus long and reflexed. The carpus is 

 produced on the exterior margin in a long 

 spine-like process at the base of the propo- 

 dus. The two following pairs of legs are not 

 prehensile, but are similar to the fourth, fifth, 

 and seventh pairs, with the exception that the 

 basis is more dilated and the carpus produced in a long wide process 

 extending half the length of the propodus. In all five pairs, the last 

 three articles are fringed with long hairs, and there is no dactylus. 

 The sixth pair is much longer than any of the others and has the 

 carpus and propodus elongate. This pair has a small blunt dactylus. 



Only one specimen was obtained by the Albatross at station 2764, 

 off Rio de la Plata, Argentina, at a depth of 11 J fathoms on sand and 

 broken shells. 



Type.— Cat. No. 42092, U.S.N.M. 



Fig. 5. Chiriscus australis. 

 Sixth leg. X 20§. 



