J04 



HARDWICKE'S SCIENCE-GOSSIP. 



of the luminous vapour floating over its surface (like 

 moonlight over rippling water) was strikingly beau- 

 tiful. The whole leaf seemed to twinkle with points 

 of light — the main ribs radiating from the common 

 centre, shining out like a silver star. These effects 

 are best witnessed after a day of hot sunshine. Some 

 further facts and suggestions which may point to a 

 possible explanation of these phenomena I reserve for 

 another paper. 



REMARKS ON DISTYLA, WITH DESCRIP- 

 TIONS OF THREE NEW ROTIFERS. 



By David Bryce. 



IN a recent article (SciENCE-GossiP, Sept. 1890), 

 my correspondent, Mr. J. E. Lord, expressed 

 his suspicion that the genusi Distyla is not a good 

 one, and he described as Cathypnre two forms of 

 which he remarked that, "when retracted they are 

 undoubtedly CathypnK, when extended as certainly 

 would they be described as Distylae." He further 



\v\ii!//'/r 



Fig. 180. — Distyla depressa. 

 Dorsal view, extended. 



Fig. 181. — Ditto, lateral. 

 X 320. 



suggested that some if not all of the species of 

 Distyla are but extended Rotifera of the genus 

 Cathypna. 



I had hoped that ere this some other observer 

 would have been induced to plead the cause of 

 Distyla, but, behold, Jove thundered and lesser 



tongues were mute. 



For myself, I cannot claim to have examined more 

 than five or six species of the two genera in question, 

 and my remarks are perhaps to be regarded as 

 provisional rather than as final. Yet there are points 



indicated by Mr. Lord, which, I think, should not 

 be allowed to pass without comment in the pages of 

 Science-Gossip. 



I would first point out that, by some misunder- 

 standing, Mr. Lord assumes that Mr. Gosse's phrase 

 "habitual protrusion of the head," refers to some 

 inability of the rotifer to withdraw its head between 

 the plates of the lorica. It is true that the figure 

 (after Ehrenberg) oi Distyla Hortie 7nanni in "The 

 Supplement " represents this species with its head 

 protruding and its cilia extended, although otherwise 

 much retracted, but I am 'inclined to deny credence 

 to that remarkable position until I see some Distyla 

 assume it. On the contrary, Mr. Gosse's words can 

 only mean that as compared with the very sluggish^ 

 timid or indolent habits of the Cathypnre, the Distylre 

 are more usually active and less prone to indulge in 

 naps (?) when under observation. All the Distylee I 

 have seen were perfectly able to retract their heads 

 within the lorica plates. 



In the next place, Mr. Lord appears to have 

 overlooked the fact that Eckstein founded the genus. 



Fig. 183.— Ditto, braiia. 



XS40. 



Fig. 182.— Ditto, ventral view. 



Distyla in 18S3 ; and it has therefore 'priority over 

 Cathypna instituted by Mr. Gosse in 1SS6, at the 

 same time that he set apart the family of the 

 Cathypnadse, to include not only Cathypna, but, inter 

 alia, the Distyla of Eckstein, which he thus distinctly 

 accepted and confirmed. If, therefore, the distinc- 

 tions set up between the two genera were shadowy 

 or insufficient, it would be the genus Cathypna that 

 would have to give way, not the genus Distyla. 



Again, if a species be so balanced between two 

 genera as to appear to belong to one when extended, 

 and to the other when retracted, there can be no 

 question that the extended position being the 

 natural one, the species must be assigned to that 

 genus to which it conforms when extended or active, 

 and I submit that on Mr. Lord's own showing, his 



