450 



THE AMERICAN NATURALIST 



[Vol. LIV 



1. The length of the worms as given does not embrace enough 

 variation, nor does the recorded width. Worms within this genus 

 have been recorded nearly twice the greatest dimensions which 

 he gives, and mature females have been found much smaller than 

 those which he describes. 



2. The ridges in the valves are not always "six main ribs on 

 each side of the central line." 



3. My experience is that the worms are dislocated from the 

 mucous membrane with difficulty and that often they are pulled 

 in two or a plug pulled out of the intestine before they can be 

 loosened. 



4. I presume that "the bar of chitin across the anterior ends 

 of the median four ' ' ridges is the structure that I have called the 

 anterior wing and its purpose is the attachment of the giant 

 buccal muscles primarily and not for "stiffening them" only, if 

 at all. 



5. Certainly not all the males have "three pairs of post-anal 

 papilla?, and one pair of pre-anal. ' ' In fact, I am sure that most 

 if not all members of this genus have seven pairs of pre-anal 

 papillae and five pairs of post-anals, with two para-anal pairs. 



6. "The semicircular flap" does not act like a bursa. The 

 action of this structure, correctly called "alee" has been ex- 

 plained by Magath (1919) and its difference from the action of a 

 true bursa shown. 



With regard to the new species ; MacCallum identified C. oxy- 

 cephalies from a Mississippi alligator. It is impossible to know 

 whether or not he really had a worm belonging to this species. 

 It would be interesting to know that a species harbored in fishes 

 could live in an alligator. If, as he says, the "general descrip- 

 tion" from the genus will answer for this species he can not be 

 certain that he had C. oxycephalies because there is nothing in 

 his general description that is specific for this worm or any other 

 species. 



MacCallum 's descriptions of C. scabra? and C. troosti are so 

 indefinite and meager that either species can not be identified 

 positively from the descriptions and figures. He gives very few 

 measurements and the magnification of the figures is not stated. 

 I had hoped to be able to compare his species with C. americanus 

 but I can find no definite data in his paper on which to base the 

 comparison. 



The description of C. chelydne is passed over with the state- 



