50 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



ovary and bends obliquely posterior toward mid-line. Vitellaria rela- 

 tively fine, acinous, from halfway between genital pore and bifurca- 

 tion of esophagus to level of anterior pair of posterior suckers. 

 Vitelline ducts unite in mid-line anterior to ovary. Common yolk 

 duct very large with diameter as great as diameter of ovary. No 

 eggs present. 



Comparisons. M. macracanthum is most similar to Octocotyle 

 minor Goto, 1894. The length of the posterior suckers in O. minor is 

 0.03 mm. as compared with 0.056 to 0.064 mm.; there are six pairs 

 of cirrus hooks as compared with five; and the large pair of posterior 

 hooks measures 0.037 mm. in length as compared with 0.100 to 

 0.123 mm. 



M. macracanthum gets its name from the fact that the posterior 

 hooks are extremely large. 



Family: MICROCOTYLIDAE Tachenberg, 1879 



Genus: Microcotyle van Ben. and Hesse, 1863 



The genus Microcotyle is a very large one. At least fifty-eight 

 species have been named. For reference purposes these species are 

 listed alphabetically with their hosts. 



1. M. acanthophallus MacCal. and MacCal., 1913 on Roccus 

 lineatus. 



2. M. acanthurum Par. and Per., 1890 on Brama rayi. 



3. M. alcedinis Par. and Per., 1890 on Smarts alcedo, Maena 

 trachini and M. vulgaris. 



4. M. angelichthys MacCal., 1913 on Holocanthus ciliaris. 



5. M. angelichthys -towns endi MacCal., 1916 on Angelichthys 

 towns endi. (Note: In the description this is written with- 

 out the hyphen as M. angelichthys townsendi. The hyphen 

 is being inserted here so that the name will be binomial and 

 comply with the rules of nomenclature. Without doubt, Mac- 

 Callum did not mean to create a subspecies.) 



6. M. archosargiA'lacCa.l., 1913 on Archosargus probatocephalus. 



7. M. australiensis MacCal., 1921 on Pomatomus saltatrix. 



8. M. australis Murray, 1931 on Sparus australis. 



9. M. bassensis Murray, 1931 on Platycephalus bassensis. 



10. M. branchiostegi Yamaguti, 1937 on Branchiostegus japonicus. 



