STUDIES ON THE DIGENETIC 'TREMATODES. 485 
of the three species of this genus. They are represented here 
in Pl. 10, figs. 25-27. 
Dr. Jaigerskidld has just sent me a paper dealing with the 
genera Spelotrema and Maritrema (in ‘ Centralbl. f. 
Bakt., etc., I Abt. Originale,’ Bd. xlviu, pp. 302-317). His 
description of Spelotrema excellens appears to agree 
very closely with mine. The elongated shape of the ovary 
is certaintly not a constant feature of the species, nor is the 
large size of the vesicula seminalis, on which Jigerskidld lays 
some weight. It is an organ which is capable of not a little 
variation in size at different times in the same animal. 
With regard to the genus Maritrema, Jagerskidld’s two 
new species appear to be quite distinct from those which I 
have previously described. He is correct in drawing attention 
to the disposition of the yolk-glands. The genus, as Jagers- 
kidld points out, shows a relationship to the MicropHALLIn», 
but it is certainly not close enough to permit of its being 
included in that sub-family. 
EXPLANATION OF PLATES 9 AND 10. 
Mlustrating Dr. William Nicoll’s paper entitled “Studies on the 
Structure and Classification of the Digenetic Trematodes.” 
The following letters apply to all the figures: 
B.S. Ventral sucker. C.B. Cirrus-pouch. D.E. Ductus ejacula- 
torius. D.St. Yolk-glands. Hz. Excretory vesicle. J. Intestinal 
diverticula. K.S#. Ovary. D.C. Laurer’s canal. M.S. Oral sucker. 
Oe. @sophagus. Ov. Ova. P.G. Genital aperture. Ph. Pharynx. 
P.Ph. Pre-pharynx. P.Pr. Pars prostatica. Pr. Prostate glands. 
T,,T,, Testes. R.S. Receptaculum seminis. S.D. Shell-gland. Uf. 
Uterus. Vg. Vagina. V.S. Vesicula seminalis. 
Fie. 1—Stephanophiala laureata (Zed.). Ventral view. x 35. 
V.P. Ventral papilla. 
