JUinot,] 22 [November 15, 



forms, but occur in all the others with the exception of Typhlolepta 

 Leidy. They are formed of a cup-shaped pigmented layer enclosing 

 a clear substance ; the open end of the cup points upward. The eyes 

 are situated underneath the dorsal epidermis, either in or below the 

 muscles, and are usually numerous. Other sense organs are unknown. 

 The sexes are always united in one individual. We distinguish sex- 

 ual glands, efferent ducts and the apparatus for copulation. The 

 testicles usually lie dorsally, the ovaries ventrally. Both may vary 

 greatly in number, in some cases there being but one gland, in others 

 two symmetrical glands, in still others numerous small ones for each 

 sex. The number of male and female glands does not always vary in 

 the same way in each species; thus Taenia has one ovary and numer- 

 ous testicles, while Distomum has also one ovary but usually only two 

 testicles. From the sexual glands run ducts, lined by a cylindrical 

 epithelium. The ducts are ramified to correspond to the number of 

 glands. The female apparatus is further complicated by the addition 

 of a singular gland, the Eggfoodstock (Volkgland, Dotterstock), which 

 produces cells, which remain alive, and pass down a separate duct, 

 that ultimately joins the oviduct. The cells are then thrown together 

 with an egg cell, and the whole cluster of cells is covered over by a 

 shell. In the Cestods and Trematods there is a widening of the ovi- 

 duct not far from the point where the food duct unites with it. This 

 enlargement has glandular walls which secrete the shell. The egg 

 as laid consists of the egg proper and the food cells which are used 

 up to nourish the egg as it grows. This curious economy is unknown 

 outside of the Plathelminths. The lower end of the oviduct is en- 

 larged and known as the uterus. There is frequently a terminal 

 chamber, the female antrum, by which copulation takes place. There 

 is also a male antrum, and we not seldom find the two sexual antra 

 united to form a single one. The sperm-duct terminates in a penis, 

 the upper end of which is enlarged and fixed, and has been named 

 Cirrhusbeutel by the Germans. The lower end (Cirrhus, penis 

 proper) can be everted, and is inserted during copulation into the 

 female opening. It sometimes has a flagellum (Dendrocoelum, Tae- 

 nia, etc.). The Trematods and Cestods have a special tube and 

 opening for the introduction of the sperma into the female apparatus. 

 This tube, known as the vagina, exists beside the oviduct (Uterus 

 auct .) , but does not exist in the Turbellarians. Stieda 1 was the first 



1 Stieda. Ueber den angeblicben inneren Zusammenhang der niannlichen und 

 weiblichen Organe bei den Trematoden. Arch, fur Anat. u. Physiol. 1871. 



