No. 3.] CLINOSTOMUM HETEROSTOMUM. 707 



As to D. aquilae, one can judge but little from the descrip- 

 tion (11): " Spatulate, cochleariform, widest behind, obtuse at 

 both ends ; mouth circular, unarmed ; acetabulum sessile about 

 as large as the mouth. Length, 3 lines; width in front, \ a line ; 

 behind, | a line. From the trachea of the Bald Eagle." The 

 type specimen, however, shows a worm similar in every respect 

 to that described as D. hcterostonmm, with the exception that the 

 anterior sucker seems to be surrounded by no elevated border, 

 and it is on this ground that I should hesitate to consider them 

 identical without further examination of fresh material. 



Up to this point I have employed the generic name, Disto- 

 mum, in speaking of the form under consideration, by way of 

 avoiding confusion, but according to the rules of nomenclature 

 now generally adopted, this generic name can no longer stand, 

 because (Railliet (16)) it is antedated by Distonms Gaertner, 

 applied to a genus of tunicates, and further, as Stiles points 

 out, because Retzius, in proposing it, arbitrarily created a syno- 

 nym for the existing generic term Fasciola. 



In the subdivisions generally adopted as a substitute for the 

 genus Distomum, this form would fall into the section mes- 

 ogonimus (Monticelli (17), '88), but Stiles and Hassall have 

 pointed out that this, in turn, is antedated by the generic name 

 Clinostomum (Leidy (10), '56), which was proposed to include 

 a group of which the type species was Clinostomum gracile, 

 a form identical with the D. retiailatiim of Looss, on which 

 Monticelli's genus was based. 



Hence, in order to concur with the modern nomenclature, 

 we can only name this form Ciinostomiim heterostomum, and it 

 will now include the larval forms formerly known, respectively, 

 as Clinostomum gracile, D. galactosomum, D. reticulatum Looss, 

 and possibly also the adult D. dimorplutin and D. aqjiilae. 



In adopting this generic name, however, it is necessary that 

 I should amplify the generic diagnosis given by Leidy (10) as 

 follows (as suggested by Stiles) : 



Family, Fasciolidae. 

 Genus, Clinostomum Leidy ('56). 

 Hermaphroditic flukes : Genital pore with cotitiguous male 



