76 STALK- AND SESSILE-EYED CRUSTACEA 
Sub-Tribe III. CaripzEa. 
Salicoques, M. Edw. (part) Hist. Nat. Crust. 1, p. 338, (1837). 
Caridea, Dana, U.S. Explor. Exped. xii, Crust. part i, p. 501, 
(1852). 
Carapace smooth, without sutures. External antenne with a large 
basal scale. The first and second pair of legs chelate, one pair or both 
often more or less enlarged; third pair not chelate. (Branchie 
folate. Carapace of thin texture). 
Prof. Dana, in his sub-divisions of the Caridea, based upon the 
researches of De Haan, relies mainly upon the form of the mandibles, 
which he considers offer four distinct types of structure. But while 
the great importance of these researches in any system of classification 
cannot be denied, this system is not free from the defects which always 
exist when the modifications of a single organ are taken as the basis 
of a system of classification, and which have already caused the 
rejection of several of De Haan’s genera by succeeding carcinologists. 
For example: by uniting in one group all the genera in which 
the mandible is of the first type, 7e., simple, slender, and inflexed, 
genera are introduced, which differ very greatly in external form 
and structure from the typical Crangonide; as in the case of 
Cyclorhynchus and Gnathophyllun, where the form of the mandible 
approaches the second type, to which these genera already belong in 
external characteristics. Moreover the difference between the third 
and fourth of the types instanced by Dana, is, I think, only one of 
degree. I may add, that the mandibles being covered externally by 
the three pairs of maxillipeds, are often very difficult of observation in 
dried specimens. I have, therefore, in the followmg arrangement of 
the families, while not neglecting other characteristics, paid regard 
primarily to modifications of the form of the two anterior pairs of legs, 
upon which Dana has based his sub-families, and which lead to an 
arrangement of the families at least as natural as that of Dana, 
Family I. CRANGONIDZ. 
Crangonens, M, Edw. Hist. Nat. Crust. 1, p. 339, (1837). 
Crangonide, sub-family Crangonine, Dana, U.S. Explor. Exped. 
xii, Crust. part i, p. 582, (1852). 
Legs of the first pair more robust than those of the second pair, 
with the mobile finger closing against the anterior margin of the palm, 
