326 M. F. DUN LOP ON MFT0P1DIA PTERYGOIDA. 



Rotifer belongs to the genus Metopidia ; and, as the first thing 

 which attracted my attention to the Rotifer was the peculiar 

 shape — suggesting the appearance of wings — I propose that it 

 might be called Metopidia pterygoids. 



The lorica is depressed, and, when viewed dorsally, is 

 pyramidal in form, with sinuous outline both laterally and 

 posteriorly; there is a slight gap or notch in the posterior 

 dorsal border, and a much deeper one in the ventral edge ; 

 there is a dorsal ridge, the outline of which, I think, is seen by 

 careful focussing ; a longitudinal rib-like line runs down either 

 side of the ridge to near the posterior end of the lorica, and 

 another rib along the sides of the wing-like extensions ; a third 

 and shorter rib-like elevation runs close along each side of the 

 centre portion of the median ridge. The foot is three- jointed, 

 with two slender decurved toes ; there is a frontal hood ; two 

 minute eye specks wide apart, and two lateral antenna in the 

 lumbar regions ; the dorsal antenna is situated over the centre 

 of the head. Size, total j±- in. (0'102 mm.), of lorica alone 

 3-i-g- in. ; the extreme width of the lorica is also ^J-^ (0'084 mm.). 



The Rotifer at first sight suggests Perty's Notogonia 

 Ehrenbergii (Hudson and Gosse's Supplement, Plate XXXIII., 

 Fig. 38) ; but, when the plate is referred to, a considerable 

 difference is observed. Notogonia is broad with four angular 

 ]3rojections posteriorly, and besides is nearly double the size. 

 Mr. Rousselet says this new species is nearly allied to 

 Notogonia, He adds in a letter to me :" Perty's work ' zur 

 Kenntniss kleinster Lebensformen ' dates from 1852. Since 

 then his species seems to have been seen twice. In 1889, just 

 before the publication of the Supplement (Hudson and Gosse's), 

 Mr. Anderson of Calcutta wrote a paper (published in 1891) 

 ' Notes on Indian Rotifers ' in which he describes Notogonia as 

 new, under the name Metopidia angulata ; his figure is rough 

 but it agrees in the main with Notogonia. In 1892 Mr. C. 

 Ternetz, in his paper ' Rotatorien der Umgebung Basels,' 

 mentions that he has found Perty's Notogonia Ehrenbergii and 

 renames it Metopidia notogonia as belonging to that genus. 

 Ternetz is a good observer ; and, if the shape of the lorica had 

 at all differed from Perty's drawing, he would certainly have 

 seen and mentioned it." It may be concluded from this that 

 Notogonia, as seen at various times and in different places, is 



