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Some ISTew Records of British Cladocera. 



By D. J. SCOURFIELD. 

 (Read May 20tTi, 1892.) 



Plates IV. and V. 



During the last three years I have repeatedly found a few 

 species of Cladocera which, although fairly well known on the 

 Continent and even in some cases in America, do not seem to 

 have been hitherto recognized as British. I am well aware that 

 it would not be wise to insist very strongly on this point in 

 regard to every one of these species, as there certainly do exist 

 some indirect references, in Baird's classic work on the British 

 Entomostraca, to forms very similar to, if not identical with, 

 two of those described below. These references can, however, 

 scarcely be looked upon as definite records, and consequently 

 have but little bearing upon the title of this paper. Moreover, 

 in each of the uncertain cases I have also seen the male. 



As further introduction appears to be unnecessary in such a 

 case as this, I will at once proceed with a short description of 

 the species referred to, numbering six in all. 



Ceriodaphnia megops, G. O. Sars (Plate IV, Figs. 1-3). — 

 This is a very fine species, and may be easily recognized, as it 

 departs rather widely from the normal type of the genus. The 

 striated shell of the female, and the greatly elongated antennules 

 of the male, distinguish it at once from all its allies, with the 

 exception, perhaps, of a doubtfully distinct form, C. cristata, 

 described in America by Prof. Birge. 



Female. — Transparent, sometimes with a tinge of pink. Large 

 antennae, always more or less pink. Head prominent ventrally, 

 with only a very shallow bay anteriorly, and a slight angulation 

 in front of the antennules. Shell rather long and somewhat 

 rectangular, the dorsal and posterior margins meeting in a 

 blunt angle. Markings consisting of faint transverse strise, very 



