ON THE SPECIES CLINOSTOMUM 

 HETEROSTOMUM. 



W. G. MacCALLUM, 



Johns Hopkins Hospital. 



RuDOLPHi (i) in 1809 described a worm found by one Andreas 

 Jurine in the oesopliagus of Ardca purpurea, and named it 

 Distonium heterostomuni. The main points in his description 

 were briefly as follows : the worm measured 3 lines in length 

 by I in width ; the anterior fourth of its body formed a distinct 

 neck ; the anterior sucker, which was large, with a triangular 

 aperture, was ventrally situated and subterminal — a swollen 

 margin surrounded it. The ventral sucker, situated near the 

 anterior, was smaller and deeper, with a more longitudinal aper- 

 ture tending to be triangular. A third orifice, situated about 

 one line behind this, was thought to give exit to the hidden 

 cirrus. The body appeared transversely striated in preserved 

 specimens : cirrus situated behind the ventral sucker. 



In 1 8 19 (2) he outlined this description in his Synopsis. 



In 1845 Dujardin (3) gave a description evidently based on 

 this one of Rudolphi, for he added no single point in the anat- 

 omy, and probably merely translated Rudolphi's words. 



Diesing (4) in 1850 very briefly repeated this description 

 without any further observations. He, however, gave another 

 reference as to its habitat, — Rosa (5), — where it is said to be 

 found under the tongue of Ardea purpurea as well as in the 

 oesophagus. 



R. Ramsay Wright (6) in 1879 described specimens from the 

 mouth of Botaurus minor and gave a figure. He discussed the 

 close relationship of D. heterostomum with D. complanatum, D. 

 kians, and D. dimorphum, and suggested that the relative size of 

 the suckers, on which much stress was laid in the differentiation 

 of these species, may have been inaccurately observed, the promi- 

 nent border about the mouth being taken for the anterior sucker ; 

 and in this suggestion one must agree with him entirely. He 



