384 Annals of the South African Museum. 



GEN. ISOCLADUS, Miers. 



1876. Isoclacliis, Miers, Ann. Mag. Nat. Hist. (4) 17, p. 228. 



1905. ,, Hansen, Q. J. Microsc. Sci. vol. 49, pt. 1, pp. 103, 



118. 



1906. Richardson, Proc. U.S. Nat. Mus. vol. 31 (1907), 



p. 114. 

 1910. Baker, TV. R. Soc. S. Austr. vol. 34, p. 84. 



ISOCLADUS TEISTENSIS (Leach). 



(Plate XXXIII. B.) 

 1818. SpJiaeroma tristensc, Leach, Diet. Sci. Nat. vol. 12, p. 345 



(??) 

 1840. ,, M. Edwards, Hist. Nat. Crust, vol. 3, 



p. 207. 



1905. (?) Hansen, I.e. p. 117. 



91906. Isockuhts magellanensis, Richardson, I.e. p. 114, fig. 18 (3). 

 1913. Exosphaeroma tristense, Tattersall, Tr. Roy. Soc. Edinb., 



vol. 49, pt. 1, p. 882, pi. fig. 1 

 (juv. 3}. 



Body perfectly smooth and glabrous. Seventh peraeon segment 

 scarcely wider than 6th in $ , with a long backward, slightly curved 

 process reaching to the telsonic apex, in 2 quite plain. Junction of 

 epimera with segments well marked, but no sutures. Epimera 

 triangular, narrowing into blunt backwardly directed processes, 

 that of 7th segment not concealing lateral portion of 2nd pleon 

 segment. Pleon quite smooth, telson more strongly convex in ? 

 than in $ , the elongate tubercles at base very obscure, apex sub- 

 acute, not produced, with a very shallow ventral groove in both 

 sexes. 



First antenna, 2nd joint one-third length of 1st, which is stout and 

 internally concave, 3rd joint f length of 1st, slender, flagellum as 

 long as 1st and 2nd peduncular joints together, 12-jointed. 



Second antenna reaching to end of 3rd peraeon segment, 1st joint 

 shortest, 2nd joint a little longer, 3rd and 4th joints subequal, a little 

 longer than 2nd, 5th joint equal to 1st and 2nd together, fiagellum a 

 little longer than peduncle, 14-jointed. 



Upper lip triangular with distal margin straight or slightly concave, 

 setose. Epistome broad proximally. 



Lower lip with the lobes oval, apically rounded, setose. 



Mandibles, cutting-edge 4-dentate in left, obscurely tridentate in 

 right, secondary cutting-edge in left tridentate, in right represented 



