No. 2322. TREMATODE FAMILY HETEROPHY I DAE— RANSOM. 539 



Specifh diagnosis. — Metagonimus: Length from a minimum of 

 about 0.35 mm. up to a maximum of 2.5 mm., commonly 1 to 1.5 mm. ; 

 width, 0.24 to 0.73 mm. Cuticular scales, 9 to 10 [i long by about 5 [j. 

 wide. Oral sucker, 48 to 110 [x in diameter. Prepharynx may reach 

 a length of 74 pt. in the extended condition. Pharynx 29 to 63 ]x long 

 by 22 to 52 [j. wide. Esophagus considerably longer than the pre- 

 pharynx, may reach a length of 143 \i.. Ventral sucker placed with 

 its long axis diagonal with reference to the longitudinal axis of the 

 body, its posterior end deflected to the right, 66 to 165 [x long by 

 55 to 114 [i wide. In relation with the genital sinus and ventral 

 sucker a crescentic muscular body or appendix somewhat similar 

 to the genital papilla in the genital sinus of Cryptacotyle. Testes 

 reach a maximum diameter of about 280 [x. Ovary 67 to 145 [x long 

 by 67 to 165 [x wide. Seminal receptacle commonly somewhat larger 

 than the ovary. Vitellaria consist of about 10 lobules in each lateral 

 field. Eggs 27.5 to 30 [x long by 15 to 17 [x wide, yellowish-red, yel- 

 lowish-brown, or dark brown in color. 



Immature stage (encysted cercaria). — On the ovary in oval cysts 

 140 to 160 [X long by 100 to 120 {x wide; on the scales and in muscles 

 in usually round cysts 126 to 160 [x in diameter; on the fins and tail 

 in round cysts enclosed in an outer membrane 40 jx or more in thick- 

 ness ; diameter over all, about 224 [x. Larva covered by small spines ; 

 suckers and intestine visible ; excretory vesicle very prominent. Re- 

 moved from capsule, larva measures in fresh condition 0.4 to 0.47 

 mm. long. Ventral sucker smaller than oral sucker. Intestinal ceca 

 extend to the posterior end of the body. Excretory vesicle containing 

 numerous highly refractile granules occupies most of the space be- 

 tween the intestinal ceca. Genital organs undeveloped. When in- 

 gested by final host immature fluke develops to adult containing 

 eggs in 4 to 5 days, oviposition beginning in 7 to 10 days after in- 

 gestion. 



Hosts. — Man; dog; cat; pig; pelican {Pelecanus onocrotalus) '^ 

 mouse (experimental infections). Immature stages encysted in 

 fishes {Plecoglossus altivelis; Carassius auratus : Leuciscus hacuensis ; 

 Scardinius erythrophthalmus; Ahramis hrama; Esox lucius; Caras- 

 sius carassius; Aspius aspius; Idus idus; Blicca bjm'kna). 



Location. — Small intestine. (Immature stages in fresh- water 

 fishes encysted in ovary, muscles, fins, tails, or on the scales.) 



Localities collected. — Formosa; Japan; Korea; Roumania. 



Leiper (1913) proposed the genus Yokogawa with Katsurada's 

 species as type, but as his paper was not published until July the 

 name is antedated by Metagonimus., which was published in May of 

 the same year. 



In addition to his papers on M. yohogawai^ Yokogawa (1913, pp. 

 45-49, 3-4) has published another paper on Metagonimus., in which 



