6o STURGES. [VOL. I. 



consist of a distinct epithelium. The capillaries are not usually 

 given off from short secondary or tertiary ducts as in D. cyg- 

 noides, but leave the primary or secondary trunks directly, so 

 they are often of considerable length. The number of flame- 

 cells varies and is seldom the same on both sides; there are 

 usually from twenty-five to thirty on a side. The excretory 

 ducts and capillaries are convoluted, owing probably to body 

 contraction. The ovary lies, in more than half the specimens 

 studied, upon the right side, in the rest of the specimens upon 

 the left; a similar right or left-handed position of the ovary is 

 described by Sommer 2 in D. Jicpaticum. The vitelline glands 

 are two small compact lobes, lying close together, one on either 

 side of the median line, just behind the ventral sucker. The 

 uterus fills the circular body with its long, intricate coil; the 

 contained eggs are thin-shelled and ellipsoidal, their axes 

 measuring 25 p and 17.5 /*. There is no cirrus, and neither 

 male nor female genital opening is especially muscular. The 

 male copulatory apparatus lies above the female apparatus and 

 opens slightly in front of it into the common genital sinus. 



The points most noteworthy in D. patellare are, externally, 

 its pan shape, internally, its lack of pharynx and cirrus, the 

 collection of its vitelline glands into two small compact lobes, 

 the elongation of its excretory vesicle, and the great length of 

 its uterus. 



Histological.--^\\z following histological points were studied: 



1. Cuticle, subcuticula, and subcuticular cells. 



2. The relation of the giant cells to nerves and muscles. 



3. Flame-cells and capillaries of the excretory system. 



i. Cuticle, subcuticula, and subcuticular cells. - -The cuticle 

 is a homogeneous, densely staining, single layer averaging 3 /z 

 thick. In the genital openings and oesophagus it becomes much 

 thicker (5 /n 6 /u.) and shows a sort of stratification, staining 

 alternately light and dark in layers parallel to the body surface. 

 It encloses the nervous cores of the sensory papillae which are 

 bulb-shaped and highly refractive, but I could find no " pore- 

 canals," ducts, or traces of nuclei. Between cuticle and sub- 

 cuticula, which are usually closely applied, a narrow space is 



- SOMMER, F. : Zur Anatomie des Leberegels, Zeit.f. wiss. Zool., Bd. xxxiv, 1880. 



