55 



allowed to form an opinion from what is known (see especially 

 Vejdovsky, »Entwick. Untersuch.«) to happen in the aquatic Oligo- 

 chaeta : nevertheless , we must still endeavour to find out these facts 

 for the Earthworms. No amount of argument much less imaginings 

 from insecure premises, can settle the matter: only direct and ac- 

 curate observation will satisfy Zoologists. 

 December 28. 1893. 



4. Rotifers related to Euchlanis lynceus, Ehrbg. 



By H. S. Jennings, Assistant in Vertebrate Morphology, University of Michigan, 



U.S.A. 



eingeg. 2. Januar 1894. 



In recent numbers of the Zoologischer Anzeiger have appeared 

 articles by Jägerskiöld (Zool. Anz., Sept. 25, 1893) and Wierzejski 

 and Zacharias (Zool. Anz., Nov. 13, 1893) setting forth the syno- 

 nymy of the Euchlanis lynceus of Ehrenberg and of other species of 

 the same genus. The list of synonyms requires, it seems to me, some 

 additions. 



While studying the E.otifera of some of the inland lakes of Michi- 

 gan in the summer of 1892 and of Lake St. Clair in the laboratory of 

 the Michigan State Fish Commission in the summer of 1893, I found 

 in great abundance the form described by Wierzejski and Zacha- 

 rias in the Zeitschrift für wiss. Zoologie, Bd. 56, Heft 2, as Bipalpus 

 lynceus^ Ehrbg. Comparison with the descriptions given by Herrick 

 of Ploesoma lenticulare (Bulletin of the Scientific Laboratories of De- 

 nison University, Vol. I. No. I, 1885) and by Vorce of Gomphogaster 

 areolaüis (Proceedings of the American Society of Microscopists, 1882 

 and 1887) showed an agreement in all essential points — though both 

 descriptions are incomplete, especially that of Vorce. In order to re- 

 move all doubt as to the identity of my specimens with those of Vorce, 

 I sent mounted specimens of the form to Dr. Vorce, who very kindly 

 compared them with his own mounted specimens and sent me photo- 

 graphs taken from the type specimen of Gomphogaster and from other 

 specimens of the same species. 



He reports that there is not the slightest doubt of the identity of 

 my specimens with his own. Hudson, even in the absence of speci- 

 mens, recognized the identity of Gomphogaster areohitus, Vorce, and 

 Ploesoma lenticulare, Herrick (Monograph of the Rotifera, Supplement, 

 p. 58). Moreover, the agreement of this form with the Bipalpus lyn- 

 ceus of Wierzejski and Zacharias is so minute that there can be 

 no question as to their identity. Jägerskiöld (1. c.) recognizes the 

 identity of Gastroschiza foveolata with Bipalpus lynceus. A complete 



