MARHsPE GAMMARIDEAN AMPHIPODA 49 



the diagnoses of other genera. Character alternatives that are known as 

 "combining characters," because of their usage in keys, are occasion- 

 ally listed in diagnoses and italicized; they reflect the necessity to state 

 a general character that is diagnostic only because it occurs in unique 

 combination with all other characters stated for the genus under 

 question; the character is not necessarily restricted to the taxon in 

 question. 



Each diagnosis has as its framework the conditions known for the 

 type-species or type-genus. In some families with few genera, the 

 diagnoses are confined to the keys. No doubt, the range of variation 

 permitted in the diagnoses is too narrow; time has not been allotted to 

 analyze the literature of each species in each genus in order to widen 

 the generic limitations because the literature is occasionally so defec- 

 tive that one would waste time to ponder, analyze, and argue possible 

 truths or to speculate on omissions. Many described species are un- 

 doubtedly misclassified. 



Brief synonymies of recently established families are given but other- 

 wise such information may be found in Stebbing (1906) or J. L. 

 Barnard (1958a). 



Type-species of each genus and their modes of selection are listed 

 below the generic synonymies. A modern reference, if available, is 

 given for the type-species. The number of species is included, along 

 with generalized distributional notes on the genus. "Littoral" includes 

 sublittoral, to 300 m; "bathyal" includes depths from 300 to 2000 m 

 (here); "abyssal" exceeds 2000 m, and "hadal" 6000 m. Some species 

 in depths exceeding 300 m are pelagic but have not been so designated 

 because of uncertain data on collecting methods. Reference to terms 

 such as "arctic, antarctic, boreal," is very imprecise because no exact 

 definitions are followed. If a genus is centered generally in the antarctic 

 as well as the subantarctic the terminology is simplified to "antarctic." 

 The "arctic" includes the Norwegian Basin and its fringes as weU as 

 the polar basin. "Biboreal" denotes occurrence in northern and south- 

 ern hemispheres; "amphiboreal" denotes occurrence in both oceans of 

 the northern hemisphere. 



Occasionally depths in meters are given where they have some inter- 

 est or precision. Distributional information in parentheses indicates 

 rarity in those situations. 



