48 



U.S. NATIONAL MUSEUM BULLETIN 292 



More difficult to assess are the roles played by the remaining 

 decapods in the economy of the island. Few if any of them are con- 

 sumed directly, and since their positions in the various food chains are 

 not knowTD, only a guess, hopefully somewhat educated, can be made 

 that at least some of the smaller shrimps add their bit to the fish 

 protein in freshwater and to that at the mouths of the streams. 



Most decapods are scavengers to some degree, and whUe on Domi- 

 nica the streams are flushed so frequently by run-off after heavy rains 

 that the potential job the shrimp and aquatic crabs might do is 

 somewhat minimized, the scavenger role played by the terrestrial 

 decapods is considerable. 



On the negative side of the ledger, it seems improbable that any 

 of the freshwater or teiTestrial crabs are destructive or harmful. 

 Perhaps in local areas Pseudothelphusa and Cardisoma might be a 

 menace to small chickens or the very young of other domesticated 

 animals; no report came to us, however, of their being objectionable — 

 even in an esthetic sense! 



Explanation of Measurements 



The length of the carapace is measured in the midline from its 

 posterior margin to the level of the posteriormost portion of the 

 orbits in shrimps and crayfishes and to the margin of the front in 

 the crablike forms. 



Abd, abdomen 



Ant, antennal region 



antPd, antennal peduncle 



antrPd, antennular peduncle 



antSc, antennal scale 



antSp, antennal spine 



Apd, apodemal pit 



Api, appendix interna 



Apm, appendix masculina 



artK, articular knob 



artM, articular membrane 



Br, branchial region 



brl, branchial lobe 



brSp, branchiostegal spine 



Bs, basis 



Car, carapace 



Card, cardiac region 



Cm, cornea 



Crp, carpus 



cvg, cervical groove 



Cx, coxa 



Dct, dactyl 



Figure 4. (key) 



End, endopod 



epBr, epibranchial region 



epGst, epigastric lobe 



Epst, epistome 



Exp, exopod 



Eyst, eyestalk 



Fgr, finger 



Fig, flagellum 



Ft, front 



Ftl, frontal region 



Gst, gastric region 



Hep, hepatic region 



hepSp, hepatic spine 



Int, intestinal region 



Isc, ischium 



L, walking leg 



Md, mandible 



Mer, merus 



msBr, mesobranchial region 



msGst, mesogastric region 



mtBr, metabranchial region 



nitGst, metagastric region 



Mxpd, maxilliped 



Orb, orbit 



Orbl, orbital region 



Plm, palm 



Pip, palp 



Plpd, pleopod 



Pirn, pleuron 



prGst, protogastric region 



Prop, propodus 



Prpd, pereiopod 



Prtp, protopodite 



Ptrg, pterygostomian region 



Ptsm, petasma 



R, rostrum 



Stic, stylocerite 



Stn, sternite 



Tel, telson 



Terg, tergum 



urGst, urogastric lobe 



Urpd, uropod 



