532 



CRUSTACEA MALACOSTRACA. 



4-jointed ; 1st and 2nd trunk-legs with highly mobile chelae having 

 spoon-shaped tips beset with brushes of long setae, the carpal segments 

 short and crescentic ; reduced epipodites on 4 anterior trunk-legs, 

 exopodites on trunk-legs in the first three genera. Many closely related 

 species distributed in fresh-water lakes in different parts of the world, 

 some in oceanic islands. Troglocaris Dormitzer, in caves in Corinthia ; 

 Xiphocaris v. Marts. W. Indies to Queensland ; Atyaephyra Brito-Capello, 

 S. Eur. ; Caridina M.-E. some 20 spp. Indo-Malay, Africa, and W. Ind. 

 Atyoida Randall ; Atya Leach, some 6 spp. scattered round the world in 

 tropics ; Limnocaridina Calm. Lake Tanganyika, gills only 4 on a side. 

 Fam. 5. Stylodactylidae Sp. B. Deep sea forms, with the 2nd maxilli- 



peds terminating in 2-lobed divisions, 

 and the two anterior pairs of trunk -legs 

 with long and tapering divisions of the 

 chelae. Stylodactylus A. M.-E. 4 spp. 

 ranging down to 600 faths. Pac. and 

 W. Ind. 



The five following families, grouped 

 about the central Hippolytidae usually 

 have the carpus of the 2nd trunk-legs 

 multiarticulate (as also have the Pro- 

 cessidae, see below), except Rhyncho- 

 cinetidae and some others. 



Fam. 6. Alpheidae. Rostrum small, 

 eye stalks covered by the edge of the 

 carapace. Mandible with a 1-2-jointed 

 palp. First trunk -legs with robust 

 unsymmetrical chelae, with which some 

 species make a peculiar snapping noise ; 

 second with minute chelae ; the 4 an- 

 terior pairs bear rounded epipodites. 

 Alpheus Fab. widely distributed, A. 

 comatularum Hasw. associated with a 

 Comatulid which it resembles in colour. 

 A. ruber M. Edw. British and Mediter- 

 ranean. Athanas Leach, A. nitescens 

 Leach, British. Alope White. 



Fam. 7. Psalidopodidae. 1st trunk- 

 legs, with both blades of the chelae 

 movable, 2nd not chelate. Body beset 

 with strong spines. Psalidopus W.-M. 

 and A. 2 spp. Indian Ocean, 400-500 

 fthms., with rudimentary eyes! 



Fam. 8. Pandalidae. Rostrum long ; palp of mandible 2-3-jointed ; 

 1st trunk -legs not chelate and only 6-jointed ; the chelate 2nd pair some- 

 times unequal. Pandalus Leach, 4 British spp. ; littoral and deep sea. 

 (Doubtful genera Heterocarpus and Chlorotocus A. M.-E. ; Nothocaris, 

 Pandalopsis and Dorodotes Sp. B.) Thalassocaris Stimps. carpus of 2nd 

 trunk -legs unjointed, powerful chelae. 2 spp. Trop. Pac. (Diaphoropus, 

 Kyptocaris and others of Spence Bate's genera are larval forms.) 



Fam. 9. Hippolytidae. Rostrum large, eyes prominent, mandibular 

 palp present or ; 1st trunk-legs chelate, short and robust, the 2nd 

 chelate but more slender, its carpus subdivided into 2- very many joints, 



FIG. 325. Zoaea of 



Mf, Mf" first, second and third 

 maxillipeds; MX' first, MX" second 

 maxilla. (After Claus.) 



Hippolyte. Mf 

 ;cond a 



