ART.i TREMATODE PARASITES OF BIRDS LINTON 25 



take their origin directly from the pharnyx, are relatively slender, 

 and extend to near the posterior end of the body. The genital pore 

 is at the posterior border of the pharynx. The seminal vesicle is 

 oval-elliptical, 0.31 by 0.15, its longer diameter transverse to the 

 body. It lies on the left side with its inner end on the median line. 

 It has muscular walls and is filled with spermatozoa. No cirrus was 

 seen. The two relatively small testes are nearly symmetrically 

 f>laced at about the posterior fourth, opposite, and about 2.8 mm. 

 from each other. The right testis is 0.52 in diameter, and 0.7 from 

 the right lateral margin ; the left is 0.38 in diameter, and 0.56 from 

 the left lateral margin. The right testis is about 2.38, and the left 

 about 2.45 from the posterior end. Ovary, length 0.46, breadth 0.56, 

 is on the median line, behind the testes, and 1.68 from the posterior 

 end. The vitellaria are lateral, beginning about 1.4 from the anterior 

 end, and are distributed along the lateral margins in clusters which 

 approach a rosette-like structure. 



Anteriorly these clusters form a single series, but in the posterior 

 half of the body they lie in a double series. The uterus, filled with 

 ova, occupies all the interior of the body from the ovary to the oral 

 sucker. It is tubular, from 0.15 to 0.30 mm. in diameter, and lies 

 in many irregular convoluted folds. The complex of genital ducts 

 in the vicinity of the shell-gland is not clearly shown in the mounted 

 specimen. The shell-gland lies at the antero-sinistral border of the 

 ovary, the oviduct lying in many folds on the ventral side of its 

 anterior border. A yolk duct, leading from the left marginal 

 vitellaria to the posterior edge of the shell-gland was noted, and 

 another from the right vitellaria was faintly indicated. These ducts 

 led to a small yolk reservoir. No seminal receptacle was seen. 



Type.—Q^i. No. 7944, U.S.N.M. 



DISTOMUM species 



Two small distomes, belonging to different genera, from the intes- 

 tine of the surf scoter {Oidemia perspicillata) ^ are here noted. (Cat. 

 No. 7945, U.S.N.M.) 



A. Figure 57 



This distome was collected July 12, 1913. 



Dimensions, life: Length 0.32 mm.; breadth 0.17; diameter of 

 oral sucker 0.033, of ventral sucker 0.048 ; ova 0.013 by 0.007. 



Dimensions in balsam: Length 0.30; breadth 0.11; breadth of oral 

 sucker 0.024, of pharynx 0.014, of ventral sucker 0.041; length of 

 pharynx 0.027. Figure 57 is a sketch of this distome stained in 

 haematoxylin and mounted in balsam. The anatomy is not shown 

 satisfactorily. The ventral sucker is weak, and can be distinguished 



