Chace, Paguridae by Wass, Thalassinidea by de 

 Man, Oxyrhyncha by Garth, and the Porcel- 

 lanidae by Haig. Schmitt's treatment, of the 

 Macrura and Anomura of the Puerto Rican area, 

 as well as his contributions on the Hippidae and 

 the. genera Callianassa and Upogebia, and Ver- 

 rill's completion of the work on Bernmdan deca- 

 pods added breadth to knowledge of distribution 

 as well as taxonomic stability. Closer at hand, 

 the studies of Lunz in South Carolina yielded 

 similar results. To this list of scholars could be 

 added the names of Borradaile, Glassell, and Pro- 

 venzano, who described new forms from the Caro- 

 linian province. The works of these and other 

 authors are given in detail in the text to follow. 



Apart from these primarily systematic studies, 

 a growing number of ecological studies have been 

 published during the past 45 years. Such results 

 are not usually cited in systematic handbooks, but 

 because this one is directed primarily to students 

 and ecologists who are often newcomers to the 

 area, brief summaries have been attempted. The 

 review of literature, though not complete, is ex- 

 haustive enough to lead to most of the published 

 material. 



Actually, few species have been studied in 

 detail. Of these, almost all are littoral species 

 easily accessible to the investigator by virtue of 

 their abundant numbers and ecological niches. 

 Beyond this, a few species of commercial value 

 such as Callinectes sajndus and Penaeus spp. have 

 been studied in detail. It is fair to say that 

 ecological studies are scarcely started. 



SYSTEMATIC DISCUSSION 



This is a review of published material. Ar- 

 rangement of families and genera follows that 

 adopted by the most recent reviser of each group. 

 Important diagnostic characters of families and 

 genera have been incorporated in keys and are 

 often repeated, in part, in species descriptions. 

 Brief diagnoses of families are included to aid 

 in identification. Diagnoses of genera are not in- 

 cluded, with some exceptions, for these exist in 

 the literature. Such treatment leads to repetition 

 but gives more complete descriptive accounts for 

 individual species. 



The general key to suborders, sections, super- 

 families, and families serves as a rough index, 

 and an attempt lias been made to arrange it 



"phylogenetically". Other keys to subfamilies, 

 genera, and species are either combined or sepa- 

 rate depending on number of genera or species in- 

 volved, and these keys are scattered throughout 

 the text. 



There is a tendency in carcinology to assume 

 a specialized background on the part of readers, 

 and beginners may find themselves troubled with 

 terms. A number of monographs have included 

 introductory glossaries and figures with detailed 

 labeling as aids, but these are not always ade- 

 quate because terminology in various suborders 

 and sections lacks consistency. 



An illustration of inconsistency follows : Among 

 shrimps, the pereiopods are often called the first, 

 second, third, fourth, and fifth walking legs. 

 Among crabs, the tendency is to call the first 

 pereiopods, chelipeds, because they are almost in- 

 variably larger than the remaining legs and are 

 the only chelate pair (except in anomuran and 

 some dromiid crabs). The remaining pereiopods 

 are then termed the first, second, third, and fourth 

 walking legs. This inconsistency seems firmly 

 entrenched and it is based on functional mor- 

 phology, the shrimps tending to have five pairs of 

 legs functionally adapted to walking, but. most 

 crabs only four. Because many shrimps do not 

 walk, legs in this group herein have been called 

 "legs," the term "walking legs" being reserved 

 for crabs. Hopefully, the use of explanatory fig- 

 ures adapted from existing works, together with 

 the glossary, will resolve most of such difficulties 



In the species accounts, no attempt has been 

 made to include complete synonymies. A great 

 deal of spadework by recent specialists has made 

 abbreviation of synonymies desirable and prac- 

 tical; therefore, most are restricted to citation of 

 original description, Hay and Shore (where appli- 

 cable),, and work of the most recent reviser. 



Many descriptions which Hay and Shore wrote 

 have been paraphrased, and many measurements, 

 descriptions of color, and ecological notes have 

 been included essentially unchanged. When avail- 

 able, more recent information has been used, and 

 for this I have depended heavily on Rathbun 

 (1918b, 1925, 1930a, 1937), Schmitt (1935a), and 

 Holthuis (1951a, 1952, 1959) for key characters, 

 color notes, and depth and latitudinal ranges. 

 For these works, specific citations in the text have 

 often l>een excluded for the sake of brevity. 



FISH AND WILDLIFE SERVICE 



