The Genus Synchceta. By C. F. Rousselet. 403 



Synchseta triophthalma Lauterborn. 

 PL VII. fig. 14. 



BIBLIOGRAPHY. 



Lauterborn, Kobert. — Wissensch. Meeresuntersuchungen aus der BioL 

 Anstalt auf Helgoland, 1894, i. pp. 207-13, 1 fig. 



Spec. Char. — Body cone-shaped, very wide and rounded in 

 front ; foot indistinct ; toe thin, style-shaped, apparently single ; 

 eyes three, one large cervical, and two frontal eyes. Lateral 

 antenna asymmetrical, large, single, situated on left side of body. 

 Size 181 fj, to 265 /x (-j-4^ to ^ in.). Marine, pelagic. 



In June 1898 Mr. John Hood found this peculiar Synchseta 

 in the sea near Dundee, and sent me some living specimens for 

 identification. I recognised it at once as the animal Dr. Robert 

 Lauterborn had discovered off the coast of Helgoland in August 

 1893, and of which he had given a rough figure and short descrip- 

 tion in his Bcitrdgc zur Mecresfauna von Helgoland. Since his 

 first capture, Mr. Hood has found it repeatedly and has sent it to 

 his correspondents, and I have no doubt it could be obtained 

 at other points along the coast during the summer months. 

 Mr. Dixon-Nuttall has made a fine and accurate portrait of it 

 (fig. 14) which gives a better idea of its appearance than any 

 amount of description. The general outline of this species is cone- 

 or top-shaped, very broad anteriorly and very slender posteriorly, 

 ending in a thin, pointed, style-like toe, which appears to be single. 

 The auricles are very large, and the front of the head is rounded, 

 and so wide as to be, with the auricles, very nearly as broad as 

 the animal is long. The usual pair of large outer frontal styles 

 project from large triangular fleshy flaps, and the two smaller 

 styles are situated on the dorsal edge just above the frontal eyes. 

 A peculiarity of this species is that it has three deep red eyes : a 

 cervical eye which is double, in the usual position, and two frontal 

 eyes situated in front, a short distance below the dorso-frontal 

 edge of the head. Two streams of minute red granules usually 

 connect the dorsal eye with the frontal eyes, as if the latter were 

 connected with the cervical eye by means of very fine tubules. 

 I have noticed a similar tendency in several other species such as 

 S. oblong a, and more rarely in & tremula, but only in S. littomlis 

 are the frontal eyes so constant and so prominent as in S. trioph- 

 thalma. The dorsal antenna is present in its usual position, but the 

 main and unique feature of this Synchreta is that it has a single, 

 very large and asymmetric lateral antenna, protruding from a 

 fleshy prominence low down on the left side of the body near the 

 toe. There is no trace of a lateral antenna on the right side. The 



