The Genus Synchwta. By C. F. Rousselet. 287 



structure. The intestine is inconspicuous, and opens dorsally 

 above the base of the foot. The gastric glands in this species are 

 more or less divided into lobes. The ovary is large, rounded and 

 .flattened, filling nearly the whole of the ventral side of the body- 

 cavity, and contains usually eight nucleated germ-cells, and often a 

 maturing egg lies by the side of it. The egg when extruded may 

 sometimes be seen attached to the toes for a very short time, but 

 soon becomes detached and falls to the bottom ; it can hardly be 

 said that S. oblonga carries its eggs, though occasionally an indi- 

 vidual may be seen with an egg attached. 



The lateral canals are distinct on each side of the stomach, and 

 end in a branch with two flame-cells near the top of this organ ; 

 posteriorly, they open into the small contractile vesicle. 



The muscles of the body are very narrow, striated, and arranged 

 as in & tremula. 



The male has often been observed by me, and is represented in 

 figs. 2a and 2b. It is small, elongated, curved ventrally, with two 

 toes and four short frontal styles, has a large red eye and large 

 sperm-sac ; its greatest length is 102 fi ( 2 ^q in.). 



Synchceta oblonga is a moderate swimmer when compared with 

 its more vigorous cousins ; it swims fairly straight forward or in 

 graceful curves, and has not the habit of anchoring itself to a thread 

 and revolving on its longer axis, which is such a conspicuous habit 

 of S. tremula. 



In size S. oblonga is distinctly smaller than tremula, but of 

 course young specimens of tremula may be smaller than adult 

 oblonga. The usual size is : female up to 225 /x (y^ in.) by 115 fi 

 (520 i n *) w i°^ e a t tne auricles. 



Synchseta grandis Zacharias. 

 PI. V. fig. 8. 



BIBLIOGBAPHY. 



Zachabias, Dr. Otto. — Forscrmngsberickte aus der Biolog. Station zu Plon, 

 Theil 1, 1893, p. 23, fig. 2. 



Spec. Char. — Body very long and slender, broadest at the 

 auricles, compressed in the middle, tapering to an elongated single- 

 jointed foot, bifurcate at the tip ; auricles large, pendent ; frontal 

 styles four; eye spherical, red, cervical. Size, total length 505 fi 

 (^q in.) by 258 //. (-^g- in.) wide at the auricles. Lacustrine. 



This is probably the largest member of this genus, and was 

 first found by Dr. 0. Zacharias in 1893 in the great inland lake of 

 Plon, in Holstein. Five years ago I obtained it from one of the 

 large reservoirs of the East London Waterworks Company at 



u 2 



