6 Cumacea 



evanescent. Pairs of pleopods in the male attached to the first five, the 

 first three, the first two, the first, or to none of the pleon segments, their 

 structure consisting of a peduncle generally carrying two rami, which are 

 never more than two-jointed. The much more conspicuous uropods are 

 always present, consisting of a peduncle carrying two rami, the exopod always 

 two-jointed, the endopod having one, two, or three joints. 



Size ranging from under 2 mm to 35 mm. 



The group has been variously classified, among the Araphipoda by 

 J. C. Fabricius, the Isopoda by Lepechin, the Macrura by Pennant and 

 Goodsir, as a larval form of Macrura by H. Milne-Edwards, Nicolet, 

 Agassiz, and Dana, among the Schizopoda by Say, Desmarest, Latreille, 

 Kossmann, among the (unrestricted) Stomapoda by I)e Kay, Bate, 

 Danielssen, placed near to My sis by Huxley, as a suborder of Mysidacea 

 by Boas, among Branchiopoda by Latreille and Stimpson, recognised as 

 an independent group by Kroyer, van Beneden (sessile-eyed Decapoda), 

 Claus (between Malacostraca and Copepoda), Fritz Miiller (nearer to stalk- 

 eved than sessile-eyed Malacostraca), Dohrn (between Edriophthalma and 

 Mysis), Paulson, "G. 0. Sars, T. Stebbing, T.Scott, Zimmer. Caiman 

 and others. Dohrn finds affinity of the group with the Isopoda by the 

 embryonal development, Delage derives it from the Tanaidae, G. 0. Sars 

 and Stappers agree in placing it between the Podophthalma and Edrioph- 

 thalma, but G. 0. Sars considers its approach nearer to the stalk-eyed 

 Crustacea, and Stappers thinks that the proximity is incontestably closer 

 to the sessile-eyed. 



Distribution in all Oceans, from shore between tide-marks to great depths, Caspian 

 Sea to mouth of the Volga. 



26 Families, 62 accepted and 4 doubtful genera, 309 accepted and 23 doubtful 

 species. 



Synopsis of Families chiefly based on male specimens: 



{Five pairs of pleopods in the male — 2. 

 Fewer than five pairs of pleopods in the 

 male — 5. 



(Four pairs of peraeopods in the male with 

 exopods 1- Fam. Vaunthompsoniidae 

 Fewer than four pairs of peraeopods in the 

 male with exopods — 3. 



{Three pairs of peraeopods in the male with 

 well developed exopods 2. Fam. Sjmipodommatidae 

 Fewer than three pairs of peraeopods in the 

 male with well developed exopods — 4. 



f No separate telson 3. Kam. Bodotriidae 



^ I Telson separate . . . • 4. Fam. Ceratocumatidae 



Three pairs of pleopods in the male — 6. 

 5 -j Fewer than three pairs of pleopods in the 

 male — 9. 



I No separate telson 5. Fam. Leptooumatidae 



\ Telson separate — 7. 



First maxillae with palp 6. Fam. Chalarostylidae 



First maxillae without palp — 8. 



{ 



