6 Crustacea and Echinodermata of the 



exist in the region now under consideration, a number 

 which seems quite large when we consider that so recently 

 as in the year 1838 not a single species was known to 

 science as forming part of its fauna.* But we cannot sup- 

 pose even this number to be more than a fourth part of that 

 which will be reached when a thorough search shall be insti- 

 tuted. Many families which are undoubtedly represented 

 here by one or more species, have not yet been noticed ; 

 and that part of the coast which is included within the 

 tropics must swarm with Crustacea of the higher orders, the 

 species of which are as yet entirely undetermined. With- 

 out, therefore, attempting to generalize upon so imperfect 

 data, we may notice a few facts with regard to the character 

 of the Crustacean fauna, which are so prominently marked 

 that they will be but little affected by future discoveries. 



The tribe Oxyrhyncha is very numerously represented in 

 the rocky fiords of the upper coast, and a predominance of 

 deep-water forms may be observed, the genera of which are 

 mostly peculiar to this region. The restricted genus Cancer 

 (Platycarcirms, M. Edw.) is remarkably well represented 

 here, by four species, very abundant in individuals, and 

 which are in fact the most common crabs known. On the 

 other hand, with the exception of a single species of Ozius, 

 no other examples of the Cancrinea, elsewhere so numerous, 

 have yet occurred ; and it is indeed singular that the sandy 

 shores of California, so well adapted to Lupa and its allies, 

 should have as yet furnished no species of the Portunidce. 

 In this point a striking difference is shown between the 

 marine fauna of this and the eastern coast, where such 

 forms are abundantly distributed. 



The chief and most noticeable feature, however, which 

 at once gives a peculiar character to the Decapoda of the 

 Northwestern coast, is the remarkable development of the 

 Lit/iodina. But few species of the rare and curious crabs 



* " Nous ne savons rien Bar les Crustaccs de la cute occklentale dc 1' Amcr- 

 14110 du Nord." Milne-Edwards. Hist. Nat. ties Crust, iii. 504, (1840.) 



