I0 g CRUSTACEA MALACOSTRACA III. 



a. Abdomen posteriorly rounded, without postero-lateial angles. First thoracic segment consider- 

 ably shorter than, or almost only half as long as, the second. 



a. Fifth joint of first pair of legs at the distal lower angle with a single seta, which is only 

 half as long as sixth joint (D. lineare G. O. S.) 



/9. Fifth joint of first pair of legs at the distal lower angle with two setae, which are almost 

 as long as sixth joint (D. clongatum Bonnier) 



b. Abdomen with produced and acute postero-lateral angles. First thoracic segment about as long 

 as the second. 



a. Basal joint of the uropods much thickened, and these joints nearly touching one another at 

 the median line of the animal, and covering the anal doors. Epimera at first and second 



segments in both sexes produced into very long processes 3. U. longispinum n. sp. 



/?. Basal joint of the uropods not much thicker than the endopod, and very remote from the 

 median line. Epimera at first and second segments produced into moderately long or 

 short processes. 

 . Lower margin of fifth joint of first pair of legs with four setae, of fifth joint of second 



pair with five setae. Somewhat small species 4. D. simile n. sp. 



. Lower margin of fifth joint of first pair of legs with five setae, of fifth joint of second 

 pair with about eight setae. Moderately large species 5. D. gracilipes n. sp. 



Section II. 



A. Uropods biramous. (Abdomen with produced and acute postero-lateral angles). 



a. Outer angle of the head at the insertion of the antennula not produced into a free, outwards 

 projecting process. Fifth joint of first pair of legs with three to five strong spines along the 

 lower margin and at the end. 



. Fifth joint of first pair of legs with four spines along the lower margin, and a fifth some- 

 what short spine just above the very long spine projecting from the distal angle. Lateral 

 margins of fifth segment scarcely concave, a little converging backwards. 6. D. politum n. sp. 



Fifth joint of first pair of legs with three spines along the lower margin, and a fourth rather 

 long spine just above the long spine projecting from the distal angle. Lateral margins of 

 fifth segment (in the male) deeply concave, and each antero-lateral angle produced and ter- 

 minating in a spine 7- D. natator n. sp. 



f. Fifth joint of first pair of legs with three spines along the lower margin, and no spine above 

 the long spine projecting from the distal angle. Lateral margins of fifth segment in both 

 sexes deeply concave, and the antero-lateral angles broadly rounded, without any spine. 



(D. coarctatum (Hansen, MS.) G. O. S.) 



b. Outer angle of the head at the insertion of the antennula produced into an oblong-triangular, 

 acute process directed freely somewhat outwards. Fifth joint of first pair of legs with only 

 two spines and an intermediate seta on the lower margin, and no spine above the very long 

 spine projecting from the distal angle 8. D. laterale (Hansen, MS.) G. O. S. 



B. Uropods without exopod. 



