Cumacea: 11. Diastylidae, 1. Diastylis 89 



Synopsis of genera: 



f Telson comparatively long — 2. 

 \ Telson comparatively short — 6. 

 I Post-anal portion of telson long — 3. 

 "■ \ Post-anal portion of telson not long — 5. 



I Peraeopods 2, 3, of adult ? not widely separated . 1. Gen. Diastylis ') 

 \ Peraeopods 2, 3, of adult $ widely separated — 4. 



fPseudorostrum in 9 strongly upturned and peraeo- 

 pods 3, 4, without exopods 2. Gen. Braehydiastylis 

 Pseudorostrum not strongly upturned, and peraeopods 

 3, 4, in 9 with rudimentary exopods 3. Gen. Diastylopsis 



J Telson with lateral spines on the post-anal portion 4. Gen. Adiastylis • 



\ Telson without lateral spines on the post-anal portion 5. Gen. Makrokylindrus 



( Maxilliped 3 in 9 without exopod 6. Gen. Paradiastylis 



\ Maxilliped 3 with exopod in both sexes — 7. 



) Lateral spines of telson few or none 7. Gen. Leptostylis 



\ Lateral spines of telson numerous 8. Gen. Ekleptostylis 



1. Gen. Diastylis Say 



1780 Onisciis (part.), Lepechin in: Acta Ac.Petrop., 1778 v.l p.248 | 1818 Diastylis, 

 Say in: J. Ac. Philad., u In p. 313 | 1825 D., A. G. Desmarest, Consid. gen. Crust., 

 p. 245 I 1829 Condylura (non Illiger 1811), Latreille in: G. Cuvier, Regne an., ed. 2 v. 4 

 p. 153 1 1831 C, Latreille, Cours Ent., v.\ p. 416 | 1840 Condylurus, H.Milne-Edwards, 

 Hist. nat. Crust., v. 3 p. 553 | 1841 Cuma (part.), Kroyer in: Naturh. Tidsskr., i". 3vi 

 p. 503 I 1843 Alauna, Goodsir in: Edinb. new phil. J., w. 34 p. 120, 129 | 1844 Diastylis, 

 De Kay, Zool. N. York, pars 6 p. 32 | 1851 Astaricilla (?), Dalyell, Powers Creator, v. 1 

 p. 224, Asteracilla, vA p. 226 t. 62 | ISod Diastylis, Bate in: Ann. nat. Hist., ser. 2 u27 

 p. 451 I 1856 Scorpionum (part.), J. V. Thompson MS. in: W. Thompson, Nat. Hist. 

 Ireland, v.-i p. 394 | 1865 Diastylis, G. 0. Sars in: Forh. Selsk. Christian., 1864 p. 156, 

 Goniacis, nom. nud. for D. S ^t. O. Sars, p. 159 | 1900 D., G. 0. Sars, Crust. Norway, 

 r. 3 p. 42 I 1900 D., Zimmer in: Fauna arctica, vA p. 420, 434 | 1909 D., Stappers in: 

 Cellule, V.25 p. 368 (alimentary system) | 1912 £)., T. Stebbing in: Ann. S. Afr. Mus., 

 t\10v p. 147. 



Pseudorostral lobes with antero-lateral corners usually little produced. 

 Telson long, post-anal portion narrowly produced, elongate, with several pairs 

 of lateral spines. Second antenna of adult 6 usually very long. Third maxilli- 

 ped with exopod in both sexes. Third peraeopod as a rule not widely separated 

 from the second in the adult female. Both pairs of pleopods in the male 

 well developed, the endopod two-jointed. Hepatopancreatic glands with three 

 pairs of lobes. 



31 species accepted, 2 doubtful. 



Synopsis of accepted species: 



I Peraeopods 3, 4, of $ with rudimentary exopods — 2. 

 I Peraeopods 3, 4, of ? without rudimentary exopods — 6. 

 j Maxilliped 3 with 2iid joint not expanded distally — 3. 

 \ Maxilliped 3 with 2iid joint expanded distally — 4. 



{Carapace with 2^^^ pair of carinae produced below to a strong 

 tooth 1. D. bidentatus 

 Carapace with 2nd pair of carinae not forming a tooth . . 2. D. dalli 



^) D. sulcatus is an exception. 



