The Genus Synchceta. By C. F. Rousselet. 399 



Synchseta baltica Ehrenberg. 

 PL VI. fig. 11, 



Synonymy. 

 Synchwta apus Plate. 



BIBLIOGRAPHY. 



Ehrenberg, C. G. — Das Leuchten cles Meeres. Abhandl. der Akad. d. 



Wissenscli. Berlin, 1834, p. 572, pi. 1, fig. 2. 

 — Die Infusionsthierchen. Leipzig, 1838, p. 437, pi. 53, fig. 5. 

 Hudson & Gosse.— The Botifera. London, 1889, vol. i. p. 126, pi. 13, fig. 1. 

 Plate, L. H. — Ueber die Botatorienfauna des bottnischen Meerbusens, etc. 



Zeitschr. f. wiss. Zool., Bd. 49, 1890, pp. 1-4. 

 Levander, K. M. — Zur Kenntniss der Wasserfauna in der Umgebnng von 



Helsingfors. Acta Societatis pro Fauna et Flora Fennica, Helsing- 



fors, vol. xii. No. 3, 1894, p. 18, pi. 1, fig. 4. 



Spec. Char. — Body very large, bell-shaped, rounded in front, 

 constricted below the auricles, tapering to a stout foot and thick 

 obtuse toes ; four frontal styles ; wide front, and large, broad 

 auricles ; eye red, cervical, with a tendency to be cleft in two 

 halves. Size 455 fi (^ in.) to 523 /i (Jg. in.) long by 245 fj, 

 ( r £ ? in.) to 270 ft (2^5 in.) wide at the auricles. Marine, pelagic 

 in the Baltic. 



The species to which Ehrenberg gave this name appears to 

 have been first found by a Dr. Michaelis in Kiel harbour in 1830. 

 It was early associated with the luminosity of the sea. because it 

 was found in sea water that was luminous, but according to 

 Ehrenberg's own account, his experiments to prove its luminosity 

 were entirely negative, as Synchreta did not shine when isolated, 

 whilst the water contained other marine organisms, such as Peri- 

 dinia, which undoubtedly were luminous. There is, therefore, no 

 valid reason for the statement that this Synchreta, or any other 

 rotifer, is connected with the luminosity of the sea. 



Ehrenberg obtained his specimen from Dr. Michaelis, and com- 

 municated his first account and drawings of this species to the 

 Berlin Academy of Sciences in 1834, the description and figures 

 being afterwards reproduced in his great work on the Infusoria in 

 1838. 



Until quite recently the real S. baltica does not seem to have 

 been again met with, or to have been searched for in its particular 

 haunts, the Baltic Sea. Mr. Gosse, in his early writings, mentions 

 a marine Synchseta which he often found and supposed was Ehren- 

 berg's S. baltica, and figured it in his Tenby. This, however, is 

 the animal now known as Synchceta gyrina of Hood. Later Crosse 

 received another, smaller and different marine species from Mr. 

 John Hood of Dundee, which he figured in The Eotifera, pi. xiii. 

 fig. 1, under the name of S. baltica. It is, however, quite clear 

 now that none of these are identical with Ehrenberg's species, and 



