94 Records of the Indian Museum. [Vol. XIX, 



acetabulum, and the opening of thf genital pore in the immediate 

 neighbourhood of the bifurcation of the intestine this genus agrees 

 with the Dicrocoeliinae ; and as regards the distribution of the yolk- 

 glands and the length of the intestinal caeca the conditions existing 

 in the present known species of Mesocoelium are intermediate 

 between or a combination of the conditions existing in the two 

 subfamilies, though the length of the intestinal caeca more nearly 

 approximates to the conditions found in the Dicrocoeliinae and 

 especially is this the case in M. megaloon Johnston and M. sociale 

 Liihe. 



The resemblance between the genera Mesocoelium and Dicro- 

 coelium becomes still more marked if we accept the view first put 

 forward by Looss (1899, p. 632), and later accepted by Braun 

 (1902, p. 97), and confine the limits of the genus Dicrocoelium 

 "to forms with leaf-Hke shape, with testes lying near or obliquely 

 behind each other and symmetrically developed yolk-glands," 

 relegating the more elongate forms to Looss' provisional genus 

 Lyperosomum. Johnston himself admits (1Q12, p. 341) that Meso- 

 coelium agrees with the Dicrocoeliinae as regards the position of the 

 ovary behind the testes, and he gives this as one of the diagnostic 

 features of the genus. The fact that the ovary may in a certain 

 proportion of cases lie on the left side of the body, as he found in 

 M. mesembrinum and as I have shown above also occurs in 

 M . sociale Liihe, instead of being on the right as is usually the case, 

 does not seem to me to have any bearing on the matter and his 

 criticism that we cannot therefore regard the positions of the ovary 

 " as of dominant importance in referring the genus to its subfamily " 

 is invalid In no specimen of this genus examined by me or by 

 any previous observer, not excluding Johnston himself, is it 

 recorded that the ovary has ever been seen to lie in front of the 

 testes. We have here a constant anatomical feature that in my 

 opinion definitely separates the genus Mesocoelium from the sub- 

 family Brachycoeliinae, in which the ovary invariably lies in front 

 of the testes, and completely justifies its inclusion by Odhner in 

 the subfamily Dicrocoeliinae Looss, 



BIBLIOGRAPHY. 



1. Braun, M. 1902 .. ''' Fascioliden der Vogel." Zool. Jahrbii- 



chcr, Syst. Abth. Vol. XVI, pp. i— 162, 

 pis. I — 8 (Jena). 



2. Cort, W. W. 1914 .. ''Some North American larval Trema- 



todes." Illinois Biol. Monographs, 

 Vol. I, No. 4, pp. I — 70, pis. i — viii 

 (Urbana, Illinois). 



3. Cort, W. W. 1915 . . ''Bgg variation in a Trematode species." 



Journal of Parasitology, Vol. II, pp. 25, 

 26 (Urbana, Illinois). 



4. Cort, W. W 1919 .. (a) '' The excretory system of a stylet 



cercaria," Univ. Cal. Pub. Zoology. 



