TREMATODE GENUS BRACHYCOELIUM — BYRD 195 



Animal Industry, I have been privileged to examine paratypes, slide 

 no. 30875, of B. meHdionalis. The slide carries two specimens of 

 the species, one mounted in lateral view, the other in surface view. 

 Observations on this material force me to the conclusion that there 

 has been some mistake in the designation of paratypes, or that the 

 species in question is to be considered as a synonym of B. trituH. 

 In the specimen mounted in surface view, the only one of the speci- 

 mens suitable for study, there is a decided break in the vitelline 

 follicles just dorsal to the line of the esophagus, separating the 

 glands into two lateral groups (pi. 9, fig. 5). Although these glands 

 spread mesad almost to the midline, the esophagus lies fully ex- 

 posed in the gap between the two groups. If in the future the same 

 condition is found to be true for the type specimen, I suggest that 

 B. meridionalis be suppressed in favor of B. trituri. 



DISCUSSION 



With the completion of the present study there are possibly 13 

 well-defined species belonging to the genus Brachycoelmm Dujardin, 

 1845, as follows : B. crassicolle^ B. hospitale^ B. obeswm, B. trituri^ B. 

 storeriae^ B. daviesi, B. meridionalis ( ? ) , B. lynchi, B. mesorchium, 

 B. georglanium, B. ovale, B. dormJe, and B. louisianae. The morpho- 

 logical characters of the members of the genus are strikingly similar 

 in every detail except for certain constant variations that seem to 

 warrant the creation of separate species. These variations are most 

 noticeable with respect to the shape and size of the body, the presence 

 or absence (?) of spines and their extent, the ratio of the sucker sizes, 

 the shape and size of the ovary, testes, and eggs, and the distribution 

 and configuration of the vitellaria. In regard to the last-named char- 

 acter there seem to be sufficient variations among the members of the 

 genus to warrant the separation of the genus into two subgeneric 

 groups. The establishment of these two groups is deferred, however, 

 to some future date. It seems sufficient at this time to point out the 

 major differences that tend to separate the species into two groups. 



In the first group, containing the species B. crassicoUe, B. hospitale, 

 B. ohesum, B. trituri, B. lynchi, B. mesorchium, B. georgianium, and 

 B. ovale, the follicles of the vitellaria lie in the fields lateral to the 

 intestinal tract and are placed in the superficial mesenchyme just under 

 the ventral, lateral, and dorsal surfaces of the body. The species 

 B. hospitale and B. trituri ( ? ) offer the only exception to this distribu- 

 tion. In B. hospitale the vitellaria are described as being found in 

 the mesenchyme lateral to the intestinal tract, but in the mesial plane 

 of the sagittal section, and arranged along a longitudinal vitelline 

 duct. It will be noted from the present study that the vitellaria in the 

 si^ecimens assigned to this species (pi. 8, fig. 1) show a marked tend- 



