I. 



Tjalfiella tri stoma Mrtsn. 



Pis. I— X. 



Th. Mortensen. Tjalfiella tristoma n. g., n. sp., a sessile Ctenophore from Greenland. Preliminary 

 notice. Vid. Medd. Naturh. Foren. Kobenhavn 1910. p. 249 — 253. 



In 1880 Kowalevsky ') gave a description of the remarkable creeping Ctenophore, Coeloplana 

 Metschnikowii, which he had detected in the Red Sea, and thus made known for the first time a 

 Ctenophore which differed from the ordinary type in not being adapted to pelagic life. Since then 

 also other divergent types of Ctenophores have been found. In 1886 Korotneff 2) described the both 

 creeping and swimming Ctenoplana Kowalevskii from the West Coast of Sumatra, which is provided 

 with small, though distinct ribs, while in Coeloplana there are no ribs at all. In 1903 C. Dawydoffs) 

 described a curious pelagic Coelenterate from near Amboina, Hydroctena Salens kit, which he thought 

 to be an intermediate form between the Ctenophores and the Hydromedusae (Narcomedusse), much in 

 the same way as another Pacific Coelenterate, Ctenaria ctenophora, was long ago declared by Haeckel 

 to be an intermediate form between the Ctenophora and the Hydromedusae. Finally in 1906 another 

 most remarkable Ctenophore without swimming plates was described by Pedaschenko^) under the 

 name of Dogielia i/ialayana ; it was found at the South-West Coast of Java. — Also the peculiar 

 Gastrodes parasiticum described in 1888 b>- Korotneffs) may be mentioned. It was first regarded by 

 Korotneff as a parasitic Medusa, later on (1891)^) as belonging to the Actiniae. As shown by 

 V. H eider 7) it can scarcely be doubted, however, that it is a parasitic Ctenophore. Korotneff gave 

 no information of the locality, where he had found the Gastrodes, stating only that it occurred in 

 Salpa fusiforiiiis and S. confederata, which are both very wideh* distributed, even cosmopolitan in the 

 warmer regions. Probably the Gastrodes will then prove to be equally widely distributed. Through 

 v. H eider its occurrence in the Mediterranean is stated. 



') A. Kowalevsky. Ueber Coeloplana Metschnikowii. Verhandl. d. zool. Section der VI. Versauiml. russischer 

 Naturf. u. Arzte. Zoolog. Anzeiger. III. 1880. p. 140. 2) A. Korotneff. Ctenoplana Kowalevskii. Zeitschr. f. wiss. Zool. 

 Bd. 43. 1886. p. 242—50. Taf. VIII. 3) C. Dawydoff. Hydroctena Salenskii (Etude morpliologique sur un uouveau 



Coelentere pelagique). Mem. Acad. Imp. St. Petersbourg. 8. Ser. XIV. 1903. 4) D. D. Pedaschenko. Eine neue tropische 

 Coelenteratenfomi. Travaux Soc. Imp. des Naturalistes de St. Petersbourg. Vol. XXXVII. 1906. p. 1—25. Taf. I— III. 5) A. Ko- 

 rotneff. Cunoctantha und Gastrodes. Zeitschr. f. wiss. Zool. Bd. 47. 1888. 6) A. Korotneff. Zoologische Paradoxen. 

 Zeitschr. f. wiss. Zool. Bd. 51. 1891. p. 613—618. Taf. XXX— XXXI. /) K. v. Heider. Uber Gastrodes, eine parasitische 

 Ctenophore. Sitz. ber d. Gesellsch. Naturf. Freunde Berlin. 1893. p. 114- 119. 



1* 



