NO. Icr.O. AMERWAX SPECIES OF SYNALPIIEUS—COUTIERE. H 



The preceding table shows the rehitive importance of the several 

 groups inhabiting the American coasts, and enumerates, without 

 description, all the species of the genus Synalpheus which are known 

 to me. There are also included a certain number of species, yet 

 unpublished, from other localities. 



This table brings out well an important fact; that is, that the 

 species of the Paitlsoni and Xeomeris groups, especially the former, 

 are the most widely distributed. This distribution accords with cer- 

 tain unspecialized characters which are found among them, namely, 

 the short cari)ocerite, the rostrum always possessing an inferior 

 vertical prolongation, continuing the ocellary beak, and the dactyls 

 slender and elongated. The disappearance of the rostral partition, 

 the elongation of the carpocerite, thick or not, and the shortening of 

 the dactjdopodites indicate forms less and less allied to the Hippo- 

 lytidse and more and more Synalphean. 



Before examining more closely the relation of the groups of species 

 to one another, I ought to mention that man}'^ of the forms described 

 have received trinomial appellations and correspond consequently to 

 what zoological nomenclature designates as varieties, races, or sub- 

 species, and to that which the botanists know under the name of 

 " petites especes." In employing the trinomial name to designate cer- 

 tain forms allied to one another, I simply wish to say that the forms 

 represented by these names appear to me to be less distant from the 

 species to which I attach them than the species is from another species. 

 Most often these subspecies come from different localities and appear 

 also to be distinct geographical races. This is, however, probably a 

 result of the fact that the localities cited were the only ones explored. 

 One should not forget that the stations noticed, rather numerous in 

 Florida and at the Bahamas, for example, are restricted to a few 

 points on the thousands of miles of shore line along the entire Pacific 

 coast and even on the Atlantic coast south of Florida. At other times 

 these secondary forms, related to species easy to determine, come from 

 the same locality as the species. This expression '" same locality," in 

 sjoite of its apparent precision, is most often very vague. Two closely 

 allied forms can find upon the same reef very different conditions of 

 life, which isolate them as completely as if a continent separated them. 

 One speciee inhabiting a sponge, another living attached by its hooks 

 upon some species of madrepore, appear to me to represent a case of 

 this sort. 



It is possible, then, that the trinomial appellation which I uniformly 

 employ does not correspond in nature to facts exactly comparable; 

 that certain of the " races," " subspecies," or " small species " which 

 it serves to designate merit a distinct specific name; that others, on 

 the contrary, may be variations incompletely fixed of a species in a 

 state of actual instability, the limits of which it has not been possible 

 for me to fix more completely. 



