M A I O I D E A. 75 



here narrow, because of the ridge on the proelabial plate. The 

 absence of this ridge in Lupa cribraria while it is present in all 

 other known Lupas, is attended by the opposite character, a great 

 breadth to the inner branch, it reaching quite to the medial line. 

 This last is a characteristic of real value, showing a generic distinction 

 between Lupa cribraria and its supposed congeners. But we fail to 

 find any good reason for putting the L. dicantha and L. cribraria into 

 one genus, separate from L. sanguinolenta, as done by De Haan. 



We are, therefore, fully sustained in pronouncing De Haan's genera 

 as often either incorrect or ambiguous in their limits. We might 

 pursue the subject farther; but these illustrations appear to be suffi- 

 cient. The errors have arisen from assuming unimportant organs as 

 a source of distinctions, and deriving the characters from the study of 

 too few forms under each genus. The objections here brought for- 

 ward do riot affect the value of his facts as detailed, or his illustra- 

 tions. Too exalted honours can scarcely be bestowed upon De Haan 

 for the extreme fidelity of both his descriptions and plates, and the 

 laborious research which they exhibit. 



I. CRUSTACEA MAIOIDEA, OR OXYRHYNCHA. 



IN the subdivisions of the Maioidea, the comparative length of the 

 legs has been assumed as an important characteristic, and on this 

 ground, they have been divided into three groups : 1, those with their 

 eight posterior legs very long; 2, those with all the legs of moderate 

 length; 3, those with the anterior legs long and these groups are 

 designated by Edwards, respectively, Macropodinea, Maiiiiea, and Par- 

 tlit'itopinea. 



But many examples show the little importance of the comparative 

 length of the posterior legs, a characteristic unsupported by any 

 others in the species. There is a species of the Macropod genus Eury- 

 podius, which but for its identity in other characters with this genus, 

 would be arranged with the Maiinea, as the legs are no longer than 

 in many species of that group. Again, the genera Doclea and Libinia, 

 as they are now united by the genus Libidoclea, so shade into one 

 another with regard to the length of the legs, that we cannot without 

 violating the most obvious natural affinities, based on characters of 

 real importance, separate them, placing part, as is done, with the 



