636 



MR. E. J. MIEES ON THE 



certain Cancroidea. They may indeed be regarded as not so 

 niucli true Oxyrliyncha as a group osculant between these latter 

 and the Cancroidea and Oxystomata. 



Nearly all subsequent authors have retained the Oxyrhyncha 

 as defined by Milne-Edwards. Dr. Strahl, however, in a 

 system of classification of the Brachyura* based mainly upon 

 characters afforded by the structure of the basal joint (basi- 

 cerite) of the antennae, separates the Parthenopinge from the 

 Oxyrhyncha, and unites them with the Calappidse and Matu- 

 tidse, which he removes from the other Oxystomata, and places 

 Oncinopiis in the vicinity of the Grrapsoid genus Hymenosoma. 

 His views were shortly afterwards adversely criticised by Stimp- 

 son tj who demonstrated the inconvenience of a classification 

 founded upon the modifications of a single organ, and necessi- 

 tating the dismemberment of the older natural groups, and in- 

 stanced several genera which would thereby be removed from 

 the place in the system to which their real afiinities wmild 

 assign tliem ; nor do I believe Dr. Strahl's views have been 

 adopted by any later carcinologist. 



As regards the primary subdivisions of tlie Oxyrhyncha, the 

 following are the principal classifications that have been pro- 

 posed. 



Milne-Edwards in 1834* j, divided the Oxyrhiuques (Oxy- 

 rhyncha) into three tribes or primary groups of equal value. The 

 first two of these, his Macropodiens and Maiens, are distinguished 

 merely by the grea^er length of the ambulatory legs of the former 

 group, in which are placed all those forms in which the first and 

 second ambulatory legs are longer than the anterior legs and more 

 than twice as long as the postfrontal portion of the carapace. 

 If this distinction were rigidly apj^lied, it would be necessary to 

 place not only nearly-allied genera, but species of the same genus 

 (e. g. Doded) in different families. Yet it is not to be denied 

 that the greater length of the ambulatory legs is often correlated 

 with important modifications of the structure of the orbits and 

 antennae. 



M.-Edwards's third group, Parthenopiens, is a perfectly natural 



-'^ Mouatsber. Akad. Wlsseiisch. Berlin, pp. 713 and 100-i (1801). 

 t Amer. Jonru. Sci. and Arts, vol. xxv. p. 139 (1803). 

 ; Histoire naturelle des Cnistaces, toI. i. p. 272 (1834). 



