C A RIDE A. 531 



Caridea. Even in the inferior group of Oplophorinje, we have one 

 genus without the palpi, and another with them much elongated. 

 The Penaeoids, also, illustrate the little importance to be attached to 

 this development of the palpus of the legs. 



"We cannot regard, moreover, in studying out the families, the 

 length of the beak, or the relative position of the pairs of antennae. 



De Haan has observed that in some of the genera, the carapax 

 behind overlaps laterally the first abdominal segment, and in others, 

 the first abdominal segment overlaps the margin of the carapax. The 

 latter must be considered as evidence of a higher grade than the 

 former, since the body is more firmly compacted by this method of 

 connexion, while the free carapax is a universal characteristic of the 

 lowest grade of the Macroura, as well as of the Anomobranchiates. 

 But we have not been able to verify his application of this character 

 in laying down his subdivisions, neither have we succeeded in apply- 

 ing it as a basis of arrangement. His " Palasmonidea" and " Alphei- 

 dea," as far as we have examined specimens of -the species, have the 

 abdominal segment overlapping the carapax, no less than the "Cran- 

 gonidea" and " Atyadea," although De Haan's. characteristic makes it 

 otherwise. 



The natural families at which we arrive from our survey of the 

 subject, are as follows : while they diverge widely from the system of 

 Milne Edwards, they coincide in part with those of De Haan, though 

 under a different general arrangement. 



1. Maxillipedes 2di breves, lamellati. 



Fam. I. CRANGONID^E. Mandibulae graciles, valde incurvatae, non 

 palpigerae, corona angusta et non dilatata. Pedum pares Imi 2dique 

 inter se valde inaequi. 



Fam. II. ATYID^E. Mandibulos crassaB, non palpigerge, corona lata, 

 parce bipartite,, processu terminali brevi et dilatato. Pedum pares 

 Imi 2dique inter se sequi, carpo nunquam annulate. 



Fam. III. PAL^EMONID^E. Mandibulae crassse, sive palipigerae sive 



