ZOOLOaY AND BOTANY, MIOROSCOPYj ETC. 193 



cells, whose nuclei are very plainly visible. These cells are covered 

 with a thin chitinous cuticle, perforated for the passage of vibratile 

 cilia, by which the animal can move over the body of its host. The 

 cilia of the ventral face are much longer and stronger than those of 

 the dorsal. Beneath the epidermis is a basal membrane containing 

 the brown pigment to which the colour of the animal is due. 



No water-vascular system was observed, but its non-existence 

 cannot be positively asserted. 



The genital organs are the most remarkable characteristics of the 

 animal. The male organs include numerous testicles and a penis 

 enclosed in a sheath ; the female organs a double ovary and pseudo- 

 vitellogen, a uterus, and vagina. The testicles are placed in the 

 anterior third of the body, and are in the form of small sacs, each with 

 a very fine duct, which unite behind the intestine and debouch in the 

 penis. The latter is a long canal of uniform diameter, which in a 

 state of repose has numerous flexions. Its walls are muscular, and 

 covered with a thin chitinous layer. It terminates in a sort of cirrus, 

 •018 mm. in diameter. 



The uterus, like the sheath of the penis, is median, and situated 

 below the latter ; it terminates towards the middle of the body in a 

 cul-de-sac, and more often than not contains an egg enclosed in an 

 ovoid shell, which has an extremely long and fine peduncle. The 

 shell and its peduncle would be secreted by the cells which line the 

 wall of the uterus. 



The pseudo-vitellogen occupies the second third of the body, and 

 has the form of numerous ramified tubes, those on each side uniting 

 towards the median line and debouching in the uterus. Immediately 

 behind these openings are the ovarian cells ; these are more or less in 

 the form of a hand, of which the wrist communicates with the uterus, 

 whilst the fingers are directed backwards and spread out. The eggs 

 develope in the extremities of these fingers, and become larger in pro- 

 portion as they advance towards the uterus. Their nuclei and nucleoli 

 are very visible. 



The vagina, which is never found in the Turbellaria, but is well 

 marked in the Trematoda, opens on the dorsal surface in the pos- 

 terior quarter of the body, and thence runs forwards towards the 

 uterus. At the plane of the opening of the ovaries it dilates into a 

 receptaculum seminis with muscular walls, which communicates with 

 the uterus by a narrow and short canal. 



This aberrant creature thus presents affinities (by the ciliated 

 epiderm, digestive apparatus, male organs, and two ovaries) with the 

 Turbellaria on the one hand, and (by the vagina and disposition of 

 the pseudo-vitellogen) with the Trematoda on the other. Seeing that 

 the young Trematoda are ciliated, but later on lose their cilia, the 

 Trematoda may be considered as modified if not degraded Turbel- 

 larians. The animal in question being, therefore, a transition form, 

 should represent a new suborder of Turbellaria. 



The author proposes to designate it Syndesmis, in order to 

 express its morphological role, and promises further details on the 

 subject. 



Ser. 2.— Vol. II. O 



