No. 5 meserve: monogenetic trematodes S3 



suckers elliptical, broader than long, with membranous septa, 0.032 

 to 0.036 mm. in length by 0.060 to 0.064 mm. in width. Genital 

 pore near anterior end, halfway from anterior end to vitellaria. 

 Genital atrium (fig. 31) armed with two sets of hooks; sixteen in 

 anterior set forming an incomplete circle, open posteriorly. Anterior 

 genital hooks long, slender, 0.024 to 0.028 mm. in length. Twelve 

 posterior hooks consisting of four strong chitinous spines with 

 slightly recurved points on each side and four other hooks posterior 

 and median pointing anteriorly and associated with a strong, mus- 

 cular sucker-like structure. The paired posterior spines 0.020 to 

 0.032 mm. in length. Testes large, smooth, almost spherical, eleven 

 in a single row posterior to ovary and extending almost to haptor. 

 Ovary in middle of body in mid-line, shaped like a question mark 

 from ventral side, right arm broader and about one half as long as 

 left arm. Oviduct arises from lower part of right arm. Seminal recep- 

 tacle spherical posterior to lower end of right arm. Vagina single, 

 straight, dorsal, median, opening dorsally posterior to level of an- 

 terior end of vitellaria. Vitellaria from just anterior to vaginal open- 

 ing to short distance into haptor. No eggs present. 



Comparisons. M. priacanthi has eleven testes as compared to 

 M. erythrini (which has ten) but differs in number, size, and ar- 

 rangement of the genital spines and the posterior suckers. M. sargi 

 has an incomplete corona of sixteen hooks in the genital atrium as 

 compared to twenty-eight. M. momyri has 120 to 130 posterior 

 suckers as compared with almost 200; its spines in the genital atrium 

 differ greatly in number, size, and arrangement. M. chiri has a simi- 

 lar cup-shaped organ in the genital atrium but has only sixty suckers 

 and twenty-five testes as compared to 200 and eleven. M. sciaenae 

 differs in number, size, and arrangement of the genital spines and 

 the number and size of the posterior suckers. 



M. priacanthi is named after the genus name of the host, Pria- 

 canthus. 



Gotocotyla acanthocybii, new species 

 (Plate 6, figs. 33-36) 



Host: Acanthocybium solandri (Guv. and Val.) 



Location: Gills 



Locality: Galapagos Islands 



Number: IS 



