132 PROGEESS OF MICROSCOPICAL SCIENCE. 



fifth of excessive resolving power had an angular aperture of 150' or 

 160°. Anyone in this country would be " surprised " to hear that its 

 highest angle was less than 170". The 'Naturalist' thinks that 

 makers should always engrave the angular aperture upon the mount- 

 ing and on the boxes of their objectives. The neatness and sufficiency 

 of this plan, however, is marred in the case of many modern objectives 

 whose screw-collar adjustment gives a wide range of powers and 

 angles. Exactly at wliat point of adjustment the measurements should 

 be made in these cases is one of the most difficult points to be settled 

 in endeavouring to obtain a uniform nomenclature in regard to the 

 W(jrks of different makers. At least for the present, until some 

 standard degree of adjustment can be agreed upon, both the highest 

 and lowest figures should be given where the range is considerable. 



Lymph Follicles in Vagind. — The ' British Medical Journal ' says 

 that Lowenstein* shows that the mucous membrane of the vagina is 

 not destitute of lymph follicles, as is generally asserted in anatcjmical 

 text-books. 



British Ostracoda. — We wish to direct attention to the fact that 

 Mr. G. S. Brady has had issued, by the Linnean Society, his splendid 

 ' Monograph of the Recent British Ostracoda.' It is a work which 

 takes its rank with the fine volume of Baird, and the more thorough 

 memoirs of Lilljeborg, Fischer, Zenker, Glaus, Sars, and others. The 

 classification is that proposed by G. O. Sars, son of the distinguished 

 Norwegian zoologist. Prof. Michael Sars, in his ' Oversigt af Norges 

 marine Ostracoder,' published in 1865. The Ostracoda are represented 

 by the little two-shelled water-fleas, about half a line or less in length, 

 which swim over the bottom or creep over submerged plants. As 

 remarked by the author, " the geographical and bathymetrical distri- 

 bution of the Ostracoda is a matter of the greatest interest as illus- 

 trating the probable condition under which the various fossiliferous 

 strata have been deposited." 



The Blind Fishes of the Mammoth Caves of America. — One of the 

 best papers we have seen for a very long time in the ' American 

 Naturalist " is that on the above subject, by Mr. F. W. Putnam, in the 

 January number. It is too long for an abstract here, but we specially 

 commend it to our readers' notice. 



Stauropteris Oldhamia. — At a meeting of the Philosophical Society 

 of Manchester (January 9th), Mr. E. W. Binney, F.R.S,, exhibited 

 some specimens of a fossil plant resembling the Psaronius Zeidleri 

 found in the Upper Foot Coal Seam, near Oldham. This si^ecies has 

 been described by Corda, in his 'Beitrage Zur Flora Der Vorvelt,' and 

 figured in jdate xi., but has not hitherto, he believed, been met with 

 in the British coal-fields. The Oldham specimen appeared to him to 

 be a petiole, of about one-eightli of an inch in diameter, and is of a 

 nearly circular form in its transverse section, two-thirds of it consisting 

 of a zone of strong parenchymatous tissue and an internal axis of 

 vascular tissue arranged in four radiating arms of an irregular oval 



* ' Centralblalt,' 35, Sept. 2iid, 1871. 



