No. 440.] 



NOTES AND LITERATURE. 



and widespread oriental species; the third is a new Pontodilus — a 

 seashore inhabitant. 



The classification of crabs is undertaken by Borradaile, who 

 thereupon describes the crabs from the Archipelagoes belonging to 

 the Catometope and Oxystomata. As before, especial stress is laid on 



is also described. Most of them are Indo-Pacific species, but two 

 occur in the West Indes. Lanchester's study of the Stomatopods, 

 based as it is on the study of individual variation will be of interest 

 and, it is hoped, of instruction to the species splitter. Excepting two 

 specimens of Pseudosquilla ciliata all the adults belong to the world- 

 wide Gonodactylus chiragra, including seven synonyms. Gonodac- 

 tylus lives on the surface of reefs and is abundant here. Squilla, 

 which demands mud to burrow in, is absent ; because the mud is. 

 This is another illustration of the law that the habitat of a species is 

 determined by its instincts. The author introduces "term" to 



Finally the Lithothamnia are described by M. Foslie, who combats 

 the erroneous notion that these Algae are more abundant in tropical 

 than in northern seas. 



Webster's "Diffusion of Insects in North America."— In the 



April number of Psyche we have a very interesting article on the 

 above subject, from the pen of Professor F. M. Webster, who has 

 already contributed various papers of the same general nature to our 

 entomological journals. 



The problem of the nature and extent of destruction of life during 

 the Glacial epoch is but barely touched upon, the intention of the 

 author being to show how post-glacial distribution has been accom- 

 plished. He points out that with the retreat of the ice three gate- 

 ways for the introduction of species into this continent were open — 

 (1) the Alaskan chain for Asiatic insects, (2) Central America for 

 forms from South America, and (3) Florida, by way of the West 

 Indies as an alternative to the Central American route. All new 

 life depending to any large extent upon land for its introduction 

 must come by some one of these three roads, the agency of man in 

 the matter being of so recent an origin as to need separate consider- 



The northwestern gateway, leading from Asia, seems to have been 

 taken advantage of by numerous Coccinellidoe and certain Chrysome- 



