12 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 124 



Externally the adhesive (or grasping) organ in fixed specimens 

 (pi. 2b, d, e) is a well-developed concave ventral depression. On the 

 basis of comparative observations on Dendrocoelopsis ezensis from 

 Hokkaido in northern Japan, the adhesive organ of D. hymanae is less 

 developed than that of D. ezensis. The histological construction of the 

 adhesive organ is illustrated in plate 2f. The subepidermal adhesive 

 surface is covered with an epithelium devoid of rhabdites and pierced 

 by numerous long gland ducts filled with a granular, eosinophilic 

 secretion. The cell bodies of the glands are most numerous dorsally 

 but also occur throughout the mesenchyme of the head region. The 

 muscular system of this organ, which could not be analyzed in detail 

 because of the poor histological condition of my slides and the density 

 of the glandular structures, has fibres attached to the entire adhesive 

 surface. This structure of the adhesive organ of the present species is 

 very similar to that of the adhesive organ of Dendrocoelopsis garmieri 

 (de Beauchamp, 1950, p. 69, fig. 2). Its muscular system is more 

 weakly developed than in Dendrocoelopsis spinosipenis (Kenk, 1925, 

 p. 133, fig. 2; Dahm, 1960, p. 16, fig. 9), or in Dendrocoelopsis ezensis 

 (Ichikawa and Okugawa, 1958, p. 13, figs. 3, 4, pi. figs. 43-68) but 

 more than in Dendrocoelopsis vaginatus (Hyman, 1935, p. 340, pi. 51: 

 figs. 1, 2) and Dendrocoelopsis vandeli (de Beauchamp, 1932, p. 257, 

 fig. 43). 



The longitudinal strip of coarsely eosinophilic gland cells in each 

 lateral margin is found in the present species; this character is common 

 in many Dendrocoelopsis species (Ichikawa and Okugawa, 1958; 

 Hyman, 1935; Kenk, 1925, 1953). It occurs both in the prepharyngeal 

 region and in the posterior terminal part of the body (some sections 

 of the body margin were lost) in the new species. 



The anterior trunk of the intestine bears eight or nine pairs of 

 lateral branches. Each posterior trunk has 13 or more pairs of lateral 

 branches. The paired, rather large ovaries, situated behind the second 

 pair of lateral branches of the anterior intestinal trunk, show no 

 histological peculiarities. The ovovitelline ducts proceed backward 

 and finally unite to form a short common ovovitelline duct at the 

 anterior level of the genital pore and open into the male antrum close 

 to the genital pore. The yolk glands or vitellaria, clusters of large and 

 darkly stained cells, occur throughout the body length between the 

 diverticula of the intestine. 



The testes are moderate in size, numerous, and ventral in position. 

 They are arranged in two zones on both sides of the midline, extending 

 from the level of the ovaries to the base of the pharynx. In the central 

 cavity of each testis occurs a tangled mass of sperm. The two sperm 

 ducts form the usual sinuous tubes packed with sperm (the spermi- 

 ducal vesicles) and are found from the level of about the middle of the 



