112 Mr. H. A. Baylis on Dicrocoelium lanceatum. 



details. These specimens, of which tliere is a considerable 

 number, were collected at Georgetown, British Guiana, by 

 Mr. G. E. Bodkin, Government Biologist, during November, 

 1915. They were kindly handed to me for determination by 

 the Imperial Bureau of Entomology. 



On a consideration of the many resemblances between 

 these examples and the typical D. lanceatum, and of the minor 

 points in which they differ from it, I am inclined to regard 

 them as belonging to a well-marked variety of that species, 

 rather than a distinct form. The one salient feature is 

 the position of the testes, which in the specimens under 

 consideration invariably lie symmetrically opposite to each 

 other in the same transverse plane. All authorities are 

 agreed in describing the testes of D. lanceatum as being- 

 placed nearly u tandem," i.e., one behind the other, but 

 somewhat diagonally, near the longitudinal axis of the body *. 

 The exact position of the testes is, as a rule, a very constant 

 specific character in Trematodes ; but in this case the almost 

 complete correspondence between the rest of the anatomy and 

 that of the typical form seems to outweigh such a considera- 

 tion. The only other differences that I have been able to 

 find are in the somewhat smaller size of the cirrus-sac and 

 the slightly larger average size of the eggs. Even the coils 

 of the uterus show complete agreement, as far as they can be 

 traced. For the sake of comparison, however, with the type, 

 it may be worth while to give a fairly full description of the 

 new variety. 



The length of the worms varies between 5 and 7 mm., and 

 the maximum widths for these lengths respectively are 

 1*62 mm. and 2 mm. The body is flattened dorso-ventrally, 

 narrowing considerably from side to side in front, and less 

 so behind. The posterior end is frequently somewhat 

 rounded; sometimes, however, it is more pointed than in 

 the example figured. To the naked eye the body is whitish 

 and semi-transparent (in spirit), the masses of fully-formed 

 eggs in the uterus being visible as blackish or brownish 

 patches. The skin is smooth. 



The oral sucker is subterminal, and has a diameter of 



* Neveu-Lemaire ('Precis cle Parasitologic humaine') gives a figure 

 of D. lanceatum (reproduced in Brumpt's 'Precis de Parasitologic,' 

 2nd ed. 1913, p. 335), in which the testes are symmetrically arranged; 

 but tliere is no reference to the source of the specimen from which the 

 original figure was drawn, and no description of the internal anatomy is 

 given in Neveu-Lemaire's work. The figure is, in other respects, very 

 rough and inaccurate. 



