SYSTEMATIC DISCUSSION 



Historical Review 



Since the original definitive work by H. Milne Edwards (1834), 

 there have been four major revisions of the oxyrhynchous crabs of world- 

 wide scope, those of Dana (1851b), Miers (1879c), Alcock (1895), and 

 Balss (1929). Between each of the dates mentioned the number of 

 genera to be considered was progressively increased : before Miers by 

 Stimpson, before Alcock by A. Milne Edwards, and before Balss by 

 Rathbun. Since, with the exception of Dana and, to a minor extent, 

 Miers, describer and reviewer were not the same person, each subsequent 

 reviewer was confronted by a confusion less and less of his own con- 

 triving. 



It should not be inferred from the foregoing statement that each 

 revision was revolutionary in character, completely upsetting the existing 

 arrangement, nor that the workers whose efforts were purely descriptive 

 were therefore irresponsible. Rather, each review rested securely upon its 

 predecessor by a generation, and it was only when the newly discovered 

 species and the genera erected to receive them failed to find accommo- 

 dation within the existing framework that the higher concepts of sub- 

 family and family were redefined. In a field which in the last century 

 and a quarter has witnessed such intense activity, this periodic bursting 

 of bounds was inevitable. 



The classification employed at present may be traced directly to the 

 three tribes proposed by the elder Milne Edwards (1834), whose Mac- 

 ropodiens and Mai'ens became the Maiinea of Dana and of Miers, the 

 latter settling upon three families, the Inachidae, Maiidae, and Periceri- 

 dae, rather than Dana's five. Reduced to subfamilies and increased to 

 four by Alcock, who withdrew the Acanthonychinae from the Inachinae, 

 these are the primary subdivisions of Rathbun (1925) and other latter- 

 day workers. The Parthenopiens of Milne Edwards have been given 

 equal rank with his other two tribes since the time of Dana. In some 

 respects Alcock's work represented a return to the earlier writers, par- 

 ticularly Dana; however, his four subfamilies of the Maiidae were an 

 improvement on Dana's five families of the Maioida, and his genera 

 were distributed in a more natural manner. The system continued to 

 suffer, however, from the predilection of Miers and Alcock for an 

 arrangement based upon orbital configuration alone. 



It is perhaps too soon to determine whether the system proposed by 

 Balss (1929) will rank with those of his distinguished predecessors, or 

 will lapse into desuetude with those of De Haan (1833-50) and Strahl 



[7] 



