66 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



P. pacifica, was found on the gills of Xurel marginatus (Gill) [syno- 

 nym: Caranx marginatus (Gill)], from Port Culebra, Costa Rica. 



P. pacifica is named after its geographic location, the Pacific 

 Ocean. The only other described species lives in the Atlantic Ocean. 



MacCallum (1918) described Acanthodiscus mirabile from Car- 

 anx hippos, and placed it in the Gyrodactylidae van Ben. and Hesse. 

 Johnston and Tiegs (1922) gave it the genus name Protomicrocotyle 

 since Acanthodiscus was preoccupied and created the new subfamily 

 Protomicrocotylinae. Poche (1925) placed it in a new family, the 

 Protomicrocotylidae. 



The writer has examined and measured the type and paratypes 

 which were sent to him by Dr. E. W. Price from the United States 

 National Museum. Not only did MacCallum misinterpret structures 

 but he also made mistakes in his measurements. The evidence from 

 the type material indicates that when MacCallum says fifteen mi- 

 crons he means 150 microns. He misinterprets the spines of the geni- 

 tal atrium and calls them the penis spines. He does not mention the 

 vagina. Price (1936), after re-examining the type material, reduces 

 the family Protomicrocotylidae to subfamily rank since it does not 

 differ enough from other microcotylids to warrant a new family. 



Cestracolpa cypseluri, new genus, new species 

 (Plate 10, figs. 75-80) 



Host: Cypselurus callopterus (Gunther) 

 Location: Gills 



Locality: Charles Island, Galapagos Islands 

 Number: 2 



Body 3.046 to 3.076 mm. in length by 0.678 to 0.695 mm. at 

 greatest width, slender, broadest throughout middle third, tapering 

 slightly anteriorly and posteriorly to middle of posterior third of 

 body where it broadens posteriorly to haptor. Posterior haptor 1.018 

 to 1.300 mm. in width, broader than greatest body width, posterior 

 border truncate with almost a straight edge bearing forty-one suck- 

 ers in one row. Posterior suckers elliptical, four times as wide as 

 long, 0.020 mm. in length by 0.080 mm. in width, located at equal 

 distances one behind the other pointing diagonally anteriorly and 

 toward the right with transverse axis at an approximate angle of 

 forty-five degrees with long axis of body. Chitlnous skeleton of 



