280 Transactions of the Society. 



A small rounded opening below the middle of the dorsal side- 

 of the mastax leads to a long, thin- walled oesophagus, which is not 

 ciliated internally, and empties in the rounded thick-walled 

 stomach. The cells of the stomach are large, often containing 

 numerous yellow oil-globules, and ciliated internally, keeping the 

 food in continual motion. The food-particles are usually green or 

 l>rown, and occasionally pink in colour. The intestine is quite 

 inconspicuous ; the cloaca is situated dorsally at the root of the 

 foot. The gastric glands attached to the stomach are spherical in 

 shape, and contain a granular centre and some nuclei. 



The ovary is rounded and more or less compressed ; usually it 

 is of the same size as the stomach, but in some animals I found it 

 twice as large, filling the greater part of the ventral half of the 

 body-cavity, and containing eight to sixteen nucleated germ-cells. 

 Maturing eggs containing a cluster of small, spherical, yellow 

 granules are often seen by the side of the ovary. The eggs, when 

 laid, fall off immediately, and are not carried about ; they are 

 spherical in shape, white, transparent, except the small cluster of 

 deep yellow granules mentioned above ; their size is 98 • 5 /x 

 (zk'g i 31 -) i Q diameter. The surface of the egg is covered with 

 minute sparsely scattered dots. It is worthy of mention that 

 Dr. 0. Zacharias has stated that in the north of Germany S. pcctinata 

 habitually carries its eggs about, attached to the toes. This is 

 very strange, considering that here in England I have never once, 

 during the many hundreds of times that I have had this species 

 under observation, seen a single S. jpectinata do anything of the 

 kind. 



The eye, seated on the granular brain-sac, is fairly large,, 

 spherical in shape and bluish-purple in colour; its structure is 

 that of a hyaline vesicle closely packed with very minute purple 

 granules. There is no sign in this species of a stream of red 

 granules forward or of frontal eyes. 



The lateral canals and flame-cells are of normal structure, but 

 reach only to the height of the stomach and gastric glands. The 

 contractile vesicle is small, situated at the base of the foot, and a 

 tubule cf the lateral canals can clearly be seen to enter it on each 

 side, after making a loop in its wall. 



The muscular system is well developed, particularly in the 

 head, where there is a complicated system of narrow, finely striated 

 muscular bands for regulating the position of the auricles and for 

 the retraction of the head. The long retractors of the head and 

 foot are very narrow and finely striated. The transverse muscular 

 bands are more numerous and more closely set around the head 

 and neck region. 



The foot is stout and short, contains two foot-glands and carries 

 two small, acute toes. 



Synchceta pectinata is a most vigorous swimmer, and its course 



