CONTRIBUTIONS TO AMERICAN HELMINTHOLOGY. 55 
of the mouth of the American Bittern (Botaurus minor, Gm.) at the 
sides of and below the tongue. 
The following species, according to V. Linstow’s excellent ‘“ Com- 
pendium,” have been found in the cavity of the mouth or in the 
cesophagus of Ciconiz : 
1. D.complantaum ....... » (OSOPMMeess 0. 0 Ardea cinerea. 
2. D. heterostomum ........ sub lingua ...... A. purpurea, 
hy ALA Le he eben abe aegeeias @eophetes «0 is Cie. alba. 
4, D. dimorphum .......... 6 TEER ELS dee e's A, cocoi. 
These forms are closely related ; indeed, Dujardin’ regards the first 
two as identical with the third, and Diesing? seems to suggest that 
the first and fourth are also related. The separation by Diesing of 
D. hians from these congeners, on account of the relative size of the 
suckers, may possibly be grounded on a mistake. The anterior end 
of the worm which I possess resembles closely that of D. dimorphum 
(see Diesing’s figure),* and it is more than probable that the promi- 
nent border which surrounds the mouth in these forms has been 
taken for the anterior sucker. This it seems to replace functionally 
in part in my specimens; for during life it undergoes rapid changes in 
shape, sometimes having a circular sometimes a triangular aperture, 
and plays an active part in the locomotion of the animal; while the 
anterior sucker is quite distinct, although small, and is immersed in 
the papilla which springs from the anterior depression. (See Fig. 1). 
The following points in the description of D. heterostomum induce 
me to refer my specimens to it until a comparison can be made: 
the habitat, size, two lateral lines, form of anterior end of body, of 
neck and of ventral sucker, position of genital organs and apertures. 
The details which follow are for the most part taken from dead 
‘specimens. 
The form of the body is subject to much variation. Fig. 1 repre- 
sents it at rest. Length, 6.85 mm.; greatest breadth, 1.5 mm. It 
may, however, lengthen into a much more linear form. The anterior 
sucker is 0.3 mm. in diameter, its aperture transversely elliptical. 
The pharynx has thin walls, is still smaller, and gives off the intes- 
tinal coeca immediately, which are very conspicuous from the deep 
brown pigment in their walls. They have the further peculiarity of 
1 Helminthes, p. 399. 2System. Helm. I. 354. 
3 Neunzehn Arten Tremat, X, B, Denkschr, d. k, Akad. in Wien., Taf, III., 2 & 3. 
