460 SUMMARY OF CURRENT RESEARCHES RELATING TO 



5. Arachnida 



Species in Hydrachnida. — F. Koenike * describes in detail a new 

 species of Eylais, obtained by Schauiuslan d's Expedition in New Zealand. 

 The new form is allied to E. infundibulifera Koen., which the author 

 believes to be a synonym of E. bi/urca Piersig ; this species he states was 

 founded by that author on a female specimen of E infundibulifera. In 

 a note upon species and synonyms in Hydrachnids, Rich. Piersig f denies 

 this, and asserts that the two species are both valid, and are distinctly 

 marked off from one another. 



North American Arachnoids.^ — Mr. N. Banks gives a synopsis of 

 North American Arthrogastra — Arachnoids '' with plainly segmented 

 abdomen, palpi of male not modified for a genital organ, rarely of small 

 size, without jointed abdominal spinnerets." He discusses the Scor- 

 pionida, Solpugida, and Pedipalpi, giving keys to their genera and 

 species. 



t, Crustacea. 



Macrura from Madagascar.§ — H. Coutiere has been able to study 

 various collections of fresh-water Macrura from Madagascar, and finds 

 that, apart from the Astacidse which have already been studied, there are 

 nineteen species or varieties belonging to the genera Palsemon, Caridina, 

 and Atya represented in the gatherings. Of the nineteen, five appear to 

 be peculiar, but some of these may be shown to have only varietal value. 

 Of the remaining fourteen, two have a much restricted distribution 

 (East Africa to Ceylon), and the remainder a wide distribution extending 

 through the Pacific to New Zealand and Samoa. The distribution of 

 the fresh- water members of the fzenus Palsemon is of much interest, both 

 on account of the occurrence in the fresh-water basins of the same region 

 of identical species (although there is no evidence that such basins have 

 ever been connected), and the occurrence of the same species in widely 

 separated regions. These peculiarities are in part explained by the 

 hypothesis that the fresh-water forms have arisen comparatively recently 

 from marine forms ; but the occurrence in Madagascar of species found 

 also in East Africa, the Malay Archipelago, and Australia ; of a species 

 P. superbus, found also in Shanghai, and possibly identical with P. 

 moorei from Tanganyika and P. trompii from Borneo ; finally of the 

 (sub-)genus Bitlujnis in Madagascar and in Chili, cannot as yet be fully 

 explained. 



New Genus of Fresh- water Isopods.|| — Mr. 0. A. Sayce describes 

 Phreatoicoides gracilis g. et sp. u., found on logs of wood in a Gippsland 

 river. Fundamental differences in the pleon necessitate a new genus, 

 but this is near Phreatoicus Chilton and Phreatoicopsis Spencer and Hall. 

 Though inhabiting surface-water it is blind, which perhaps points to a 

 near ancestry in caves or subterrauean waters. Another noteworthy 

 characteristic of this form is the apparent dimorphism in the males. 



* Zool. Jahrb. (Abth. Syst.), xiii. (1900) pp. 125-32 (7 figs.). 



t Zool. Anzeig., xxiii. (1900) pp. 209-13. 



t Anier. Nat., xxxiv. (1900) pp. 421-7 (4 figs.). 



§ Compter Rendus, cxxx. (1900) pp. 1266-8. 



|| Proc. R. Soc. Victoria, xii. (1900) pp. 122-38 (3 pis.). 



