new or little-known Infusoria. 219 



This species, which I have met with only once, at Sorrento, 

 among the seaweeds on the shore, is very well characterized 

 by its flat fornij and especially by its four dorsal costa?, cha- 

 racters which prevent its being confounded with the other 

 known species. 



Urceolus Ahnizim^ Mereschk. 1877. 

 (PI. XII. fig. 13.) 



In my Russian memoir, already mentioned, on the Pro- 

 tozoa of the north of Russia, which appeared in 1877*, I 

 described a new genus of Infusoria belonging to the order 

 Flagellata, which I called Urceolus^ and met with in the 

 White Sea. A year later, in 1878, appeared M. Stein's book 

 on the Flagellata, under the title of ' Der Organismus der 

 Infusionsthiere/ Abth. iii., in which he figures (pi. xxiii. 

 figs. 42-48) an organism which he describes in the explana- 

 tion of the plates as a new form, giving it the generic name 

 of Phialonema. On comparing the Phialonema cyclostomay 

 Stein, with my Urceolus Alemzini, I saw in a moment that 

 the former was only a new species belonging to my genus 

 Urceolus J established in 1877. 



The genus Urceolus is characterized by the presence of a 

 neck of greater or less length, with a wide aperture at its ex- 

 tremity, leading into a rather deep conical canal, at the bottom 

 of which is situated the buccal orifice ; it is also at the bottom 

 of this canal, a little to one side, that the single flagellum 

 originates. The genus has two species : — 



1. Urceolus Alemzim, Mereschk. 1877. — Surface of the 

 body smooth, without striee ; neck cylindrical, with the mar- 

 gins abruptly truncated and not turned out. Loc. White 

 Sea. 



2. Urceolus cyclostomus (Stein), Mereschk. 1878. — Sur- 

 face of the body furnished with spiral striee ; neck obliquely 

 truncated, and with the margin turned out. Loc. ? 



It is not right to regard, as I formerly did f, the aperture 

 at the extremity of the neck, and through which the flagellum 

 issues, as the buccal aperture, this latter being placed much 

 more in the interior of the animal, at the bottom of the conical 

 fossa situated in the interior of the neck. 



* In the Travaux de la Soc. des Naturalistes de St. Petersb. vol. viii. 

 t C. Meieschkowslii, " Studieu iiber Protozoen des nordlichen Russ- 

 lands," Archiv fiir ruikr. Anat. Bd. xvi. 1879, p. 188. 



