88 Addison E. Verrill, 



habit. The structure and form of the dactyl hooks are important 

 because directly related to their habits. 



Their colors are various according to their habits. The sexes 

 are often very different in color, but both may be variable. Some, 

 if not all, are able to change their colors by means of the chromato- 

 phores. 



All are capable of making an explosive sound with the large 

 chela, like the species of Alphcus, when disturbed, but they lack 

 the sucker-like disks on the dactyl and anterior end of the palm. 



Some of the species are remarkable for the large size of their 

 eggs, which are sometimes considerably over I mm. in diameter 

 and much fewer than in ordinary species of Alphcus. The young 

 of such species, accordingly, are hatched in an advanced stage of 

 development (my sis-stage). Others have numerous small eggs 

 and hatch in a zoea-stage. 



Brooks and Herrick (op. cit., 1892) claimed that the same 

 species inhabiting different localities may produce larvae differing 

 very widely in form and structure, as well as widely different 

 sizes of eggs. But the form studied by them, that produced small 

 eggs from which hatched zoea-like larvae, proved to be a true 

 Alpheus (A. packardii). See above under A. packardii. 



Yet they demonstrated that closely allied species of this group 

 have larvae that differ widely in the state of development when 

 hatched, as well as eggs differing greatly in relative sizes. 



According to Coutiere (op. cit, pp. 2, 3, 1909) the Alpheus 

 saulcyi var. bremcarpus of Brooks and Herrick is a distinct 

 species, while under A. saulcyi var. longicarpus at least two other 

 species, viz. : v$\ longicarpus and S. pcctiniger C. were included, 

 as determined by the types. The last two and the former belong 

 to different sections of the genus. 



Typical v$\ longicarpus has small eggs and coca-like larvae, while 

 S. pectiniger and S. brevicarpus have very large eggs and mysis- 

 llkc larvae. 



The species to which Coutiere restricts the name, vS\ in in us, has 

 small eggs, their diameter being less than I mm., which give rise 

 to zoea-like larvae, as do many other species. It is very unlike the 

 A. minus of Brooks and Herrick. 



M. Coutiere, op. cit., 1909, described twenty-five American 

 species of this genus, besides about twenty-one named varieties 

 and subspecies, and more recently he has added another species. 



