Glossary of Terms 



See figure 4 (p. 49) for illustrations of morphological characters 



Abdomen (Abd). The "tail" or that part of the body posterior to the cephalo- 



thorax, consisting of six body segments or somites and the telson. 

 Antenna, pi. -nae. The more lateral of the two paired flagellate appendages 



projecting anteriorly from the anterior end of the body. 

 Antenna! peduncle (antPd). The basal segments of the antenna, from which the 



flagellum arises. 

 Antenna! region (Ant). The area on the lateral surface of the carapace of shrimps 



posterior to and encompassing the antennal spine. 

 Antennal scale (antSc). The laterally rigid lamellate exopod of the antenna of 



shrimps and crayfishes. 

 Antennal spine (antSp). A short spine usually present on or near the anterior 



margin of the carapace of shrimps just ventral to the orbit. 

 Antennxilar peduncle (antrPd). The basal segments of the antennule, from which 



the fiagella arise. 

 Antennule. The more mesial of the two paired flagellate appendages projecting 



from the anterior end of the body. 

 Apodemal pit (Apd). Any of several often unpigmented depressions on the carapace 



of many crabs indicating the origin of an invaginated element that forms 



part of the internal thoracic skeleton. 

 Appendix interna, pi. -dices -nae (Api). A slender rodlike lappet on the mesial 



margin of the endopod of the second through fifth pleopods of shrimps; 



it is provided with terminal hooked setae by which the two pleopods of a 



pair may be joined mesially. 

 Appendix masculina, pi. -dices -nae (Apm). A lappet inserted between the appendix 



interna and the mesial margin of the second pleopod of most male shrimps. 



The presence or absence of an appendix masculina is the easiest way to 



distinguish males and females in most caridean shrimps, and in some families, 



such as the Atyidae, it is greatly enlarged, dwarfing the superimposed 



appendix interna, and it offers important taxonomic characters. 

 Areola. See "Cardiac region." 

 Articular knob (artK). A swelling or irregularity in the integument at a joint, 



as on either side of a chela at the base of the movable finger or between the 



abdominal somites at the juncture of the terga and pleura. 

 Articular membrane (artM). The uncalcified integument at a joint, permitting 



movement of the exoskeleton, as between the podomeres of a pereiopod. 

 Basis, pi. -ses (Bs). The second segment from the proximal end of a typically 



7-segmented appendage. 

 Branchial lobe (brL). A boss located at the anteromesial angle of the mesobranchial 



region on tlie carapace of certain crabs. 

 Branchial region (Br) . The portion of the carapace overlying the branchial cavity, 

 in the true crabs comprising the epibranchial, mesobranchial, and meta- 

 branchial regions and the branchial lobe. 

 Branchiostegal spine (brSp) . A short spine on or near the anterior margin of the 



carapace of some shrimps ventral to tlie antennal spine and dorsal to the 



anterolateral angle of the carapace. 

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