ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 4IJ9 



bottom. Pasijylia'e and Parapasiplia'e seem to be abyssal species, but 

 to be free-swimming ; the eight species of Penfeidse which are in the 

 list are undoubtedly free-swimming forms not confined to the im- 

 mediate region of the bottom, but their relatively small eyes and 

 well-developed ocular papillae indicate that they are deep-water, if not 

 abyssal species. 



The author provisionally groups the species into four classes: 



1. Species inhabiting the bottom or its immediate neighbourhood. 



2. Species probably not confined to the immediate neighbourhood of 

 the bottom, but showing structural evidence of inhabiting abyssal 

 depths. 3. Doubtful, but probably inhabiting abyssal depths. 

 4. Species probably not inhabiting abyssal depths. 



Many of the species are remarkable for their large size, and there 

 are none that are very small ; many are large members of, or even 

 giants in the families to which they belong. The colour of the 

 abyssal Decapoda is very characteristic; a few species are nearly 

 colourless, but most are of some shade of red or orange; bright 

 markings were not seen in any species from below 1000 fathoms. 

 The structure of the eyes is of the highest interest, and worthy of 

 the most minute and careful investigation, but Mr. Smith has not 

 yet been able to make it. He gives, however, the results of a " super- 

 ficial examination of the external characters of the eyes." The 

 simplest and most direct form of the tendency to modification is seen 

 in the gradual reduction in the number of the visual elements. Some- 

 times the eyes are highly modified (as in Fentacheles), and here all the 

 species have probably been long inhabitants of deep water ; when the 

 eyes are less modified, or obsolescent, the species are much more 

 closely allied to shallow-water forms. Many Decapods have the 

 eggs large in size and small in number, but this is not true of all ; 

 when the eggs are large development is, as in Bythocaris leucojpis, 

 abbreviated. 



Revision of the Astacidse.* — Mr. W. Faxon, working on this 

 group as represented in the Museum at Harvard, adopts the division 

 of the family Astacidse with the sub-families Potamohiinse and Paras- 

 tacinse. The first sub-family comprises forms occurring in Europe, 

 Asia, and North America ; and include the two genera Astacus and 

 Camhariis. Of the genus Astacus, fourteen species are described ; 

 these are widely distributed over Western North America, over the 

 western portion of the Europeo-Asiatic continent, and over Eastern 

 Asia. The genus is not known in Siberian rivers flowing into the 

 Arctic Ocean, nor between Lake Baikal and the Ural Mountains. Of 

 the genus Cambarus, fifty-two species are described, all of which are 

 confined to America, with the exception of one blind species occurring 

 in the caves of Carniola. The description of the Parastacinse will 

 appear in a second part. 



'Challenger' Schizopoda.t — Professor G. 0. Sars reports that 

 the collection of Schizopoda made by H.M.S. 'Challenger' was both 



* Mem. Mus. Corap. Zool. Cambridge, x. (1885). 



t Report of the voyage of H.M.S. ' Challenger,' xiii. (1885) 228 pp. (38 pis.). 



