Hood — On the Rotifera of the County Mayo. 673 



Rhinops vitrea, Hudson. This is a rare and attractive species. I met 

 with but two examples in a lake at Castlebar in 1889. 



R. orhicidodiscus, Thorpe, J. E. Microsc. Soc, 1891, p. 304, pi. yii. 4. 

 Bilfinger, Kotatorienf. "Wurttembergs, pi. xi., 2, 3. A number of 

 specimens of this rare and recently-described form occurred in a 

 bog-pool near Westport, 1891. This species was originally obtained 

 by Dr. Thorpe in October, ] 889, in the mountains of Donegal. 

 The generic affinities of this species remain doubtful. The ab- 

 sence of proboscis and of eyes mark it as very different from 

 R. vitrea, and make it, perhaps, worthy of a new generic appella- 

 tion. The resemblance to Hydatina does not seem so striking as 

 Thorpe suggests it to be. 



Notops hjptopus, Ehrenb. I met with many examples, both male and 

 female, of this species, in a bog-pool near Westport, in June, 1891. 



N. minor, Eousselet, Joum. Quekett Club, Jan. 1892, p. 359. Many 

 examples in a marsh near "Westport, August, 1892. 



Ploesoma lenticular e, Herri ck, Bull. Sci. Lab. Denison Univ., I. 1 

 1885. "An undescribed Eotifer," Yorce, Proc. Am. Soc. 

 Microsc. 1882 ; Gomphogaster areolatus, Id., ibid., 1887, (cf. H. 

 and Gr., Suppl., p. 68, pi. xxxiv., 36). Gastropus ehrenlergiii^'), 

 Imhof, Zool. ^Anz., xi., p. 171, 1888 (Ascomorpha (?), sp.. Id. 

 ibid. X. p. 577, 1887). Gastroschiza foveolata, Jagerskiold, Zool. 

 Anz., XV. p. 447, 1892 ; Levander, Acta Soc. pro Fauna et Flora 

 Fennica, xii. 3, p. 25, 1894. Bipalpiis lynceus, Wierz. and 

 Zach., Z. f. w. Z., Ivi., p. 236, 1892. Ploesoma lynceus, Jennings, 

 Zool. Anz., xvii., p. 55, 1894. Bull. Mich. Fish Comm., No. 3, 

 p. 13, 1894. 



(Plate XXIII. j fig^s. 9^ 9a.) 



The multitude of synonyms under which this Eotifer is 

 placed give a measure of the perplexity that it and its near 

 allies have caused to students of the group. First recorded in 

 1882 by Yorce, who found it in Lake Erie near Cleveland, Ohio 

 it was again found not very long afterwards in the same State by 

 Herri ck, who described and named it in 1885 ; and the name 

 given by the latter writer thus takes precedence over that given 

 by the original discoverer, who delayed publishing a description 

 of his species under a definite name till 1887. 



Passing over the brief and obscure notice of Imhof, who, if 

 this species was really under his observation, described it under 

 the generic name Ascomorpha, Perty, a synonym of Sacculus, and 

 afterwards coupled it under the new generic name Gastropus 



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