6 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



EXPLANATION OF TERMS AND ABBREVIATIONS USED. 

 Glossary of terms used in classification and description. 



Abdomen, or tall, the jointed or hinder part of the body which is reduced in 

 size and is bent forward under the thorax. In this work the abdomen is 

 considered as consisting of seven segments, inclusive of the telson. It 

 is much wider in the female than in the male. 



Afferent channels, the openings through which water passes to the branchiae. 

 In the Brachyuran crabs they usually open behind the pterygostomian re- 

 gions and in front of the chelipeds, save in certain of the Oxystomata where 

 they open at the antero-lateral angles of the palate or endostome. 



Ambulatory, or walking legs, usually four pairs, are behind the chelipeds. 

 They may be only 3 in number, as in the genus Cymopolia where the hind 

 pair of thoracic legs are delicate and tendril-like, as if used for attachment 

 to foreign objects. 



Antennae, or second pair of antennae, that pair of antennae situated between 

 the antennules and the orbits. 



Antcnnules, or antennae of the first pair, those antennae lying near together, 

 either side of the median line. 



Arm, the merus of a cheliped. 



Basis, or basipodite, the second segment (from the body) of a leg or maxilliped. 



Branchial region (paired), the very large Intersil area of the carapace, behind 

 the cervical suture. 



Buccal cavity, or buccal cavern, the cavity on the ventral surface of the body, 

 in which are situated the mouth-parts ; it is bounded anteriorly by the 

 epistome, laterally by the free edges of the carapace. 



Carapace, or cephalothorax, the shell which covers the dorsal surface, and the 

 lateral portions of the ventral surface, of the body. 



Cardiac region, the median area of the carapace, behind the cervical suture. 



Carpus, or carpopodite, the fifth segment (from the body) of a leg or a 

 maxilliped. 



Cervical groove, the complex groove, or series of grooves, running across the 

 carapace, the groove being transverse at the middle, then turning on each 

 side obliquely forward and outward to the lateral margin. It separates 

 the hepatic and gastric regions from the branchial and cardiac regions. 



Chela, or claw, the two last segments of a cheliped. 



Cheliped, the pair of thoracic legs immediately behind the maxillipeds or jaw- 

 feet. They bear the chelae or pincer-claws and are usually stouter, some- 

 times much stouter than the succeeding or walking legs. 



Coxa, or coxopodite, the first or proximal segment of a leg or a maxilliped. 



Dactylus, or dactylopodite, the seventh or terminal segment of a leg or max- 

 illiped. The dactylus is the movable finger of a cheliped. 



Distal, farthest from the center of the body; opposed to proximal. 



Efferent channels, the channels through which water passes from the branchiae; 

 they open rt tlio sides of the endoston.ie, except in the subtribe Oxystomata 

 where they open at the middle of the endostome. 



Endognath, the inner or principal branch of the maxilliped. 



Endostome, or palate, the roof of the buccal cavity. 



Epigastric lobes, the anterior lobes of the gastric region. 



Epistome, the transverse plate forming the anterior border of the buccal cavity, 

 its sides being fused with the carapace. 



Exognath, the outer or secondary branch of the maxilliped. 



Eyebroui, a term here applied to the narrow surface in the fiddler crabs between 

 the upper border of the orbit and the orbital cavity itself. 



