342 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



Discussion. The variation in the position of the posterior testis seems 

 to be determined by pressure from the cirrus sac. When the cirrus sac is 

 large and extends very far forward, it pushes the testis forward even until 

 it may be anterior and to the left of the ovary. The fact that in such speci- 

 mens the testis is misshaped by such pressure indicates that it may have 

 been done by the process of killing the worm under a cover glass. 



Prosorhynchus gonoderus, new species 

 (Plate 33, fig. 16) 



Host: a yellow-spotted grouper 



Location: Ceca 



Locality: James Island, Galapagos 



Number: Many. 2 specimens, immature, of what is probably 



the same species were collected together with P. 



ozakii from what seemed to be the same species of 



fish from Isabel Island, Mexico. 



SPECIFIC DIAGNOSIS OF PROSORHYNCHUS GONODERUS 

 Body elongate, somewhat flattened, widest posterior to rhynchus 

 where there is a fairly distinct expansion of the body, tapering gradually 

 from this region to a pointed posterior end. Length 1.480 to 2.295 ; width 

 0.380 to 0.510. Rhynchus very well developed, muscular, flattened ante- 

 riorly, pointed conelike posteriorly, longer than wide, width 0.247 to 

 0.307. Mouth far anterior, between ^ and 54 body length from anterior 

 end; pharynx 0.562 to 0.076 in diameter; saclike intestine directed for- 

 ward. Gonads far anterior, well in front of midbody, clumped together 

 overlapping one another. Ovary subspherical, at level of pharynx, to the 

 left, close to intestine, slightly pretesticular, overlapping dorsally the an- 

 terior testis. Vitellaria in 2 lateral groups, not much extended longitudi- 

 nally, tending to be 2 or 3 follicles wide, extending from level of pharynx 

 to the rhynchus, usually overlapping posterior end of the rhynchus. Pos- 

 terior limit of vitellaria (which is only slightly more or less than that of 

 the pharynx) never more than ^ body length from anterior end of body. 

 Uterus does not extend anterior to ovary but does extend posterior to 

 genital pore. Mehlis' gland posterior to ovary, among the three gonads. 

 Eggs golden yellow brown in color, 27 to 31 by 15 to 19 /a, usually about 

 27 lO 28 by 17 jx, shells rather thick. Testes subspherical, diagonally 

 placed; anterior testis to the left, overlapping ovary; posterior testis 

 slightly separated, to the right, overlapping anterior testis. Cirrus sac 

 large but, because of the far anterior location of the gonads, does not usu- 



