DECAPOD CRUSTACEANS OF THE WEST INDIES 227 



Pleopod (PIpd). One of the paired appendages typically arising from each of the 



first five abdominal somites. In the shrimps, they are primarily swimming 



organs; in the true crabs, they are modified for attachment of the eggs in 



females and as sexual appendages (two anterior pairs) or absent (three 



posterior pairs) in males. 

 Pleuron, pi. -ra (Pirn). One of the paired lateral flaps on each side of the first 



five abdominal somites in shrimps and crayfishes. 

 Podomere. Any one of the segments of an appendage, such as a segment of 



a pereiopod or maxilliped. 

 Pre-anal carina. A rigid keel protruding from the ventral midline of the sixth 



abdominal somite between the insertions of the uropods in certain shi'imps. 

 Propodus, pi. -di (Prop). The sixth or penultimate segment of a typically 7- 



segmented appendage. 

 Protogastric region (prGst). A paired anterolateral area on the gastric region of 



of the carapace of crabs. 

 Protopodite (Prtp). The fused proximal segments (coxa and basis) of an appendage, 



such as a pleopod, usually bearing an endopod and an exopod. 

 Pterygostomian region (Ptrg). The paired anterolateral area on the lateroventral 



surface of the carapace of crabs on each side of the mouth area. 

 Rostrum, pi. -tra (R). The "head spine" or anterior projection of the cephalo- 



thorax between the eyes of shrimps or crayfishes. 

 Somite. A body segment, especially of the abdomen. 

 Spelean. Living in subterranean habitats. 

 Sternite (Stn). One of the five transverse fused plates of the sternum indicating 



the basic segmentation of the cephalothorax. 

 Sternum, pi. -na. The ventral surface of the cephalothorax between the coxae of 



the pereiopods. 

 Stylocerite (Stic). A spine arising from the lateral margin of the first segment of the 



antennular peduncle in shrimps. 

 Taxon, pi. taxa. Any taxonomic unit such as an order, family, genus, or species. 

 Telson (Tel). The terminal segment of the abdomen. 

 Tergum, pi. terga (Terg). The dorsal portion of each of the first five abdominal 



somites between the pleura. 

 Thelycum, pi. -ca. A specialized genital modification of the three posterior sternites 



in female penaeidean shrimps. 

 Troglobitic. Pertaining to obligate inhabitants of caves and underground water 



systems. 

 Urogastric lobe (urGst). A very short transverse area bordering the posterior 



margin of the metagastric region on the carapace of crabs. 

 Uropod (Urpd). A paired biramous appendage attached to the sixth abdominal 



somite in all but the true crabs and usually combining with the telson to 



form a tail fan. 

 Walking leg (L). Any nonchelate pereiopod. 

 Xeric. Arid, lacking in moisture. 



