1921] NATURAL SCIENCES OF PHILADELPHIA. 161 



posterior. As far as I could observe, there is no importance in the 

 first of these distinctive characters, the changes of form in Tren- 

 tonia being much greater than is generally thought, and as for the 

 general shape of the body, if Cienkowsky's Vacuolaria virescens 

 proves to be in accordance with the above-mentioned diagnosis, 

 Senn's Vaciiolaria viridis, which according to Pascher is intermediary 

 between Trentoriia and Vacuolaria, is in fact like Trentonia being 

 described as inversely pyriform (verkehrt birnformig), rapidly nar- 

 rowed at the tail-like posterior end, strongly broadened and ex- 

 cavated anteriorly. On the same page 177, Pascher adds a note: 

 "We must probably reunite with Vacuolaria Stein's Coelomonas, 

 which differs from the former only in the possession of a single 

 flagellum. The second flagellum, which lies very close to the body, 

 probably escaped Stein's attention." 



As for Gonyostomum, or more especially Diesing's Gonyostomum 

 semen which is synonymous with Ehrenberg's Rhaphidomonas 

 semen, it is nothing but a Trentonia again, but one in which are found, 

 under the periplast, small highly refracting rod-like bodies which 

 at times develop as cilia. Speaking of Rhaphidomonas, S. Kent 

 (20) writes as follows: "Excepting for the presence of numerous and 

 variously distributed trichocysts it closely resembles Coelomonas," 

 and Stokes (34) says of his Trentonia flagellata: "This is very simi- 

 lar to Rhaphidomonas semen (Ehrbg.) Stein, with two flagella and 

 no apparent trichocysts. When first observed it was without hesi- 

 tation identified with the above-mentioned European form." In 

 the classical treatise of Engler & Prantl (12), one reads, page 171, 

 concerning Coelomonas: "Doubtful genus. Like Vacuolaria, but 

 with only one flagellum. Stein has probably missed the second 

 flagellum. . . . The genus Coelomonas Stein must also very 

 likely be abandoned." 



Between all these Flagellates, Vacuolaria viridis, Coelomonas 

 grandis, Trentonia flagellata, and even Goniostomum semen, the 

 differences are so obscure, the general form of the body, the tri- 

 angular reservoir, the chromatophores — everything, in fact, is so 

 identical, that it is difficult to fancy anything but one and the 

 same organism; in Coelomonas, the second flagellum, which in Tren- 

 tonia is at the very limit of visibility, might not have been detected ; 

 in Rhapidomonas, the trichocysts have been exaggerated in their 

 appearance. However it may be, it is as Trentonia flagellata Stokes 

 (33), undoubtedly identical with what I have seen myself, that I 

 shall consider the curious Flagellate we now come to speak of. It 



