No. 5 meserve: monogenetic trematodes 3S 



2. B. epinepheli (Yamaguti, 1937) n. comb, on Epinephelus 

 akaara. 



3. B. hendorfin (von Linstow, 1889) on Sciaena aquilla. 



4. B. ishikawae (Goto, 1894) on Lethrinus sp. 



5. B. macrocolpa (Liihe, 1906) on Rhinoptera javanica. 



6. B. melleni (MacCallum, 1927) n. comb, on Spheroides annu- 

 latus, etc. 



7. B. monticelli (Parona and Perugia, 1895) on Mugil auratus. 



8. B. ovata (Goto, 1894) on Anthias schlegell 



9. B. seriolae (Yamaguti, 1934) n. comb, on Sebastodes aureo- 

 vittata. 



10. B. sciaenae (van Beneden, 1858) on Sciaena aquilla. 



11. B. sebastodis (Yamaguti, 1934) n. comb, on Sebastodes 

 inermis. 



12. B. sekii (Yamaguti, 1937) n. comb, on Pagrosomus unicolor. 



Benedenia isabellae, new species 



(Plate 4, figs. 1-2) 



Host: Unidentified, spotted, grouper-like fish 



Location: Gills 



Locality: Isabel Island, Mexico 



Number: 5 specimens 



Body elongated oval, 3.282 to 5.113 mm. in length by 1.820 to 

 2.5 mm. in greatest width. Posterior haptor circular, not indented, 

 0.848 to 1.56 mm. in diameter, with irregularly notched, relatively 

 wide marginal membrane. The anterior pair of hooks 0.118 to 0.424 

 mm. in length, straight, sharply pointed at one end, truncated at 

 the other end. Middle pair of hooks 0.271 to 0.424 mm. in length, 

 fairly stout, straight except for a recurved point. Posterior pair of 

 hooks 0.08 to 0.10 mm, in length, with fine, recurved point. Larval 

 hooks not seen. Anterior suckers elliptical, with slightly elevated 

 margins but without marginal membrane, 0.220 to 0.339 mm. in 

 length by 0.305 to 0.390 mm. in width. Oral sucker broader than 

 long, 0.220 to 0.339 mm. in length by 0.388 to 0.557 mm. in width, 

 indented to form two to five lobes. Esophagus short, intestinal limbs 

 with lateral branches. Testes approximately in mid-body, side by 

 side and close together, with slightly lobed or crenate margin, longer 

 than wide, 0.736 to 0.996 mm. by 0.520 to 0.693 mm., pierced by 

 sixteen to twenty dorso-ventral muscles. Posterior to testes are two 



