Cumacea: 11. Diastylidae, 3. Diastylopsis 



111 



themselves concealed by those of segment 3, which in both sexes are strongly 

 produced backwards: 4*^^ segment very long, tirmly united to the 3^ 5^^ with 

 a pair of ventral teeth. 5*'' pleon segment not longer than 6*^: telson in 6 



^^^ 



Fig. 66. 



D. dawsoni (^ juv.) S. I. Smith (after Caiman). 



as long as preceding segment, with 9 pairs of lateral spines, in 9 y^^^^ of 

 preceding segment, with about 4 pairs of lateral spines. Antenna 1, 2'^'^ joint 

 shorter than 3*^, accessory flagellum 2-jointed. Antenna 2 

 Q of 4 joints, the 3*^ long. Maxilliped 3, the long 2"'^ joint 

 much widened distally, medial and lateral apices both pro- 

 duced, 3^ joint 3 times as wide as the 4*^. Peraeopod 1 

 uncommonly short, 2"*^ joint much longer tlian rest of limb. 

 Peraeopod 2, b^^ joint nearly twice as long as 6**^ and 7*^ 

 combined; 3*^ and 4**^ pairs in 9 with minute rudimentary 

 seemingly 1-jointed exopod. Peduncle of uropods twice as 

 long as the telson in 9 but less than that in the d, more 

 than twice the endopod but less than twice the exopod: 1^* 

 joint of endopod equal to the 2"^ and longer third combined. 

 L. 9 14-5 mm. d 9 mm. 



Queen Charlotte Islands, 203 m, and other parts off W. coast 

 of N. America from Alaska to California, at depths 13- 57 m. 



3. D. elongata Calm. 1911 D. e.. Caiman in: Tr. zool. Soc. 

 London, v. 18 iv p. 312, 379 t. 37 f. 1—12. 



Pseudorostral lobes straight, acute, slightly raised in 9 , 

 not in d, antero-lateral corners rounded, serrate, with the sinus 

 above them slightly marked; carapace compressed, smooth; eye- 

 lobe with no distinct eye, ending in a minute tooth in 9 only. 

 Pleon segment 1 with backward pointing medio-ventral tooth, 

 o*'^ not much longer than 6*^, its postero-lateral angles spini- 

 form, telson differing little in length from the 6^^ segment, with about 8 pairs 

 of lateral spines and a short apical pair in the 9 , a little longer and narrower 

 in the d. Antenna 1. 3*^ joint longer than 2"*^, flagellum 3- or 4-joiuted. 

 accessory 2- or 3-jointed. Antenna 2 of 9 3-jointed. Peraeopod 1, 2"*^ joint 

 considerably longer than rest of limb, with tooth at distal medial corner, 

 5^^ and 6*'' subequal. each longer than ?*■''; peraeopod 2 9, 2^*^ joint con- 

 siderably longer than rest of limb, 2"*^, 3^, and 4*^ each with small tooth 

 at distal medial corner; rudimentary exopods of 3*^ and 4*'^ peraeopods in 9 

 2-jointed: peraeopod 2 d, 2'^'^ joint scarcely longer than rest of limb, 5*^ joint 

 much instead of little longer than 4*^, B^^'^ longer than 7*^ which ends in 

 2 little carved claws; peraeopods 3, 4, 2"*^ joint toothed at lateral apex, in 

 1, 5 the 3*^ joint toothed at medial apex. Peduncle of uropods once and 

 a half as long as the telson, slightly less than that in proportion to the 



Fig. 67. 



D. dawsoni (S 



juv.) S.I.Smith, 

 carapace and 



pedigerous seg- 

 ments (after 

 Caiman). 



