FOUK NEW SPECIES OF TKEMATODE WORMS OF THE 

 SUBFAMILY ONCHOCOTYLINAE 



By Dr. G. a. MacCalltjm 



Baltimore, Md. 



INTRODUCTION 



For many years the differentiation of species among the Onchoco- 

 tylinae has been in a state of great confusion. The name Onchoco- 

 tyle appendiculata has been given indifferently to many different 

 forms, and others have been set apart as distinct species without 

 sufficient warrant. This, as usual, has resulted from the extremely 

 incomplete study of the various worms found, and from the misin- 

 terpretation of organs and the neglect of characteristic features. 

 Even now, although the anatomy of these forms has become fairlj' 

 clear, their systematic arrangement is full of difficulties, because the 

 meagerness of description makes comparison so nearly impossible. 



The literature has been so well reviewed by Cerfontaine (1900) in 

 his admirable paper that it is unnecessary to repeat it, and indeed 

 his success in collecting practically all known forms for renewed 

 study makes it impossible to do otherwise than accept his conclu- 

 sions. Only one new form seems to have been described since his 

 paper; namely, O. somniosi from So7nniosus Tnicrocephalus (sleeper 

 shark), by David Causey (1926). 



Cerfontaine divides the subfamily Onchocotylinae into three gen- 

 era: Acanthonchocotyle^ Squalonchocotyle^ and Rajoiwhocotyle. 

 Acanthonchocotyle includes forms in which the penis is armed with 

 spines; eggs with a single filament; parasites of Scyllidae, Squal- 

 onchocotyle includes forms with large mouth sucker; rectangular 

 fixation disk without intestinal ramifications within it; vaginal ori- 

 fices near the same level as the genital atrium, the two vaginal canals 

 remaining separate to their union with the yolk duct ; eggs with two 

 polar filaments; parasites of Squalidae. Rajonchocotyle includes 

 forms with small mouth sucker with transverse orifice, large round 

 fixation disk with ramifications of the intestine within it; vaginal 

 orifices behind the level of the atrium, the vaginal canals uniting 

 in a single median canal; eggs without polar filaments and at most a 

 small tubercle at one or both ends, and with meridional thickenings 

 or ribs; parasites of the Rajidae. 



No. 2892.— Proceedings U. S. National Museum. Vol. 79. Art. 26. 



66547—31 1 



