144 SUMMARY OF CURRENT RESEARCHES RELATING TO* 



such birds into three sets : — (1) the BatitaB, where the posterior limbs 

 have become greatly developed, (a) for aquatic progression (Hesperorni$)> 

 or (b) for terrestrial progression (ostrich, &c. ); (2) birds in which the 

 fore-liinbs, though useless for flight, are important agents in aquatic pro- 

 gression (penguins) ; (3) birds like Didus and Stringops, which appear 

 to possess no compensatory advantage for the loss of functional fore- 

 limbs, and are apparently degenerate. Examples of each of these three 

 sets are described by the author, who also discusses their probable origin 

 and relations. 



INVERTEBRATA. 



Limnoplankton of Russia.* — E. Minkiewicz describes various new 

 Protozoa and Rotatoria found by him in Lake Bologoie' and Lake 

 Glubokoie. In regard to the specimens of Difflugia in the lakes — pre- 

 viously described by him as D. planctonica sp. n. — he now finds that 

 there is considerable individual variation. This fact leads him to the 

 conclusion that all the plankton " species " are to be regarded as varieties 

 of D. lobostoma, the varieties being the result of the varying environ- 

 mental conditions in the different lakes. 



Potamoplankton of the Volga.f — W. Zykoff gives a brief list of 

 Microphyta, Protozoa, Rotatoria, and Crustacea found by him in the 

 Volga at Saratow. As indicated by the list, the Volga plankton has a 

 generally West European character. 



The author further notes J that during his investigations he found 

 Plagiostoma lemani var. quadrioculata in mud at the bottom of the river. 

 This Turbellarian has not hitherto been described in Russia, and further, 

 is rather a lake than a river form. 



"Sapropelic" Fauna. § — Dr. R. Lauterborn uses the term " sapro- 

 pelisclie " to denote the organisms found in the muddy debris covering 

 the bottom of stagnant fresh-water pools. The stuff consists largely of 

 vegetable remains, abounds in species of Oscillatoria and bacteria, and in 

 its black under layers smells strongly of sulphuretted hydrogen. Rhizo- 

 pods are represented by Pelomyxa palustris, Pamphagus armatus sp. n., 

 &c. ; Flagellates include Mastigamoeba trichophorum sp. n. ; the Volvocine 

 Spondylomoritm quaternarium is also characteristic. It may be said that 

 the Infusorian fauna is well defined. Rotifers are scarce, but Gastro- 

 tricha abound. The author describes Pelamphora biitschlii g. et sp. n., 

 Dactyl ochlamys pisciformis g. et sp. n., and a number of new species. 



Northumberland Marine Investigations.!! — Alexander Meek, who 

 edits this report, describes the results of some trawling excursions, 

 gives statistics of the numbers and sizes of fishes caught at different 

 times, discusses the food and the time of maturity of various flat-fishes, 

 states the results of experiments on " waste ova," and so on. Prof. 

 G. S. Brady discusses the marine microfauna as a source of food supply. 

 Mr. Meek has also faunistic notes on the Mysidse of Cullercoats and the 

 Cumacea of Northumberland, and Mr. G. P. Bulman adds to his list of 

 marine molluscs of Northumberland. 



* Zool. Anzeig.. xxiii. (1900) pp. 618-23 (18 figs.). t Tom. cit., pp. 625-7. 



X Tom. cit., pp. 634-5.; § Op. cit., xxiv. (1001) pp. 50-5. 



|| Northumberland Sea Fisheries Committee, Rep. Scient. Investigations for 

 1900, 82 pp. 



