CONTRIBUTIONS TO AMERICAN HELMINTHOLOGY. 59 
intestine can be made out in D. hepaticum depends entirely on the 
dark contents: the bifurcation was here observed from the dorsal 
surface, but the branches were empty. The longitudinal muscular 
fibres are strongly developed on the ventral surface, and the ventral 
surface of the neck has two sets of oblique decussating fibres, as in 
D. hepaticum." The transverse vitello-duct can be easily seen with 
the naked eye. The right half is longer than the left, and the com- 
mon duct, leading obliquely upwards (towards an Ootype ?), is nar- 
rower than either. 
4,—DiIsTOMUM VARIEGATUM. Rud. 
In looking for Polystomum-eggs from a specimen of Rana halecina, 
Kalm, in the way recommended by Zeller,” I found that a worm 
had been voided by the frog, which turned out to be D. variegatum, 
Rud. It had been partly macerated from exposure to the water ; 
the acetabulum was consequently even more than ordinarily difficult 
to make out, and the characteristic coloration was destroyed. The 
application of picrocarminate, however, is particularly suceessful in 
rendering distinct the different organs in Trematodes, and probably 
more so in such a case as this from the previous bleaching.” 
_ The intestinal coeca were entirely destitute of contents, and their 
epithelial lining (average individual cells of which [Fig. 7] measured 
superficially 0.03 mm. x 0.021 mm.) was well seen. 
The left lung of the same animal yielded only one well-coloured 
example of the worm. 
My examples agree well with Pagenstecher’s description and 
measurements,“ except that the ventral sucker was easily discover- 
able in the fresh worm, and that the testes, three in number, which 
seemed to be composed of flask-shaped cells empty of their contents, 
and with the neck of the flasks converging to the vas deferens, could 
hardly be called small. The vitelligenous glands, as Blanchard has 
already figured,” are in the form of six or seven scattered racemose 
clumps on each side, with a connecting longitudinal stem. 
11 Leuck. Mensch. Par., I., 537. 
12 Zeit. fur. wiss. Zool. XXVIL., p. 255, f. n. 
18 After writing the above, I notice that the use of picrocarminate has been already recom- 
mended by Dr. G. Duchamp (Journal de Micrographie, July, 1878). 
14 Trematodenlarven und Trematoden, p. 41. 
15 Ann. des Sci. Nat. 38, VILL, PL 13, f. 1. 
