i8 95 . A PASSAGE-AT-ARMS OVER THE AMPHIPODA. 265 



that there is no single distinguishing character except such as is 

 afforded by a longer or shorter slit in the apical segment of the tail. 

 This is a character about as variable as any that could have 

 been selected. Its worthlessness is proved, not only by its allowing 

 species the most incongruous to be grouped together, but still more 

 by its requiring species the most closely related to be placed in 

 different genera. 



It sometimes happens that a spiteful reviewer will pick out a 

 solitary defect in a book and make believe that it is characteristic 

 of the whole. The present criticism can scarcely be open to such a 

 charge, because it is certain that the fault imputed is that which 

 Professor Delia Valle regards as one of the special merits of his per- 

 formance. For this reason I the less regret that want of space 

 prevents me from discussing with any fulness the treatment to which 

 the Orchestidae have been subjected. These include some of the 

 most generally known Amphipoda. They enjoy the uncommon 

 advantage of having English names. From a difference of habitat, 

 obvious to the ordinary observer, some have been called shore- 

 hoppers, and some sandhoppers. Professor Delia Valle unites a 

 shorehopper found in England with an English sandhopper of a 

 different genus, and calls them both by the name of a third distinct 

 species found in Chili. To "the common shorehopper," Ovchestia 

 gammarellus, he attributes a vast synonymy. For disentangling right 

 from wrong in this list, many pages of discussion would be needed. 

 But if anyone will take the trouble to examine the question in regard 

 only to the three New Zealand species, he will wonder on what 

 fantastic principle such a list can have been framed. Variability, 

 indeed, after the usual fashion, is pleaded. One notable point is the 

 expansion of certain joints in the seventh pair of thoracic feet of the 

 adult male. Of the three New Zealand species, one has this expan- 

 sion, the other two are without it, and, of these two, one has the joints 

 of the sixth pair of feet expanded, which is not the case in either of 

 the other species. There are other differences, and, in fact, the three 

 forms, so far from being one and the same species, belong to three 

 distinct genera. 



If human nature were not the paradoxical thing it is, there would 

 be something amazing in the contrast between the lightness of touch 

 with which Professor Delia Valle creates and the heaviness of hand 

 with which he demolishes. Among several subordinate instances of 

 this which might be adduced, one assumes a not inconsiderable 

 importance. 



There is a strange parasitic or semi-parasitic Amphipod which 

 was first found in the Mediterranean many years ago by the Rev. 

 F. W. Hope. It was named Guevinia nicaensis by Achille Costa, and 

 is nearly related to, if not identical with, the species later called 

 Trischizostoma raschii by Esmark and Boeck, a mouth-filling generic 

 name which unfortunately supersedes the preoccupied Guevinia. This 



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