132 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 121 



Thynnus. In either case, Caligus thymnus is an incorrect original 

 spelling and must be emended to Caligus thynni Dana. Caligus 

 thynni Pillai (1963), a distinct species from Euthynnus affinis, thereby 

 becomes a junior homonym. 



After the pubhcation of Caligus thynni Pillai, the author of the 

 name became aware of the problem of homonymy and submitted 

 a manuscript ("Copepods parasitic on Indian marine fishes — a 

 review") containing the replacement name Caligus asymmetricus. 

 During this period, however, specimens of the species had also been 

 found on a fish captured near Green Island, Queensland, Australia, 

 and had been submitted to Z. Kabata for identification. After 

 corresponding with Pillai and learning of the replacement name 

 that was then in press, Kabata submitted a manuscript containing 

 the replacement name as well as a description of the sjoecies. It 

 is unfortunate that the manuscript containing Pillai's replacement 

 name was not published prior to the publication of Kabata's manu- 

 script. Since, however, Kabata (1965b) was the first to publish 

 the replacement name, he, therefore, becomes the author of that name. 



The present author deeply appreciates the helpful correspondence 

 with Dr. Pillai and the discussion with Dr. Kabata concerning some 

 of the above details. 



Material.— One adult female and 3 males (USNM 112912) from 

 the external sm-face of Euthynnus yaito (Jordan and Evermann) 

 captiu-ed off Moku Manu Island, near Oahu, Hawaii. One adult 

 female (USNM 112913) from the gill cavity of Euthynnus yaito (Jor- 

 dan and Evermann) captm-ed at French Frigate Shoals (USFWS, 

 HMS cruise 39, station 32). 



Measurements. — (In mm) 2 females and 3 males: 



female male 



Total length, excluding caudal setae 3. 00, 3. 35 3. 15, 2. SO, 2. 55 



Length of cephalothorax, including frontal region 1. 95, 2. 05 2. 03, 1. 88, 1. 68 



Width of cephalothorax 1. 58, 1. 65 1. 55, 1. 53, 1. 30 



Length of genital segment 0. 80, 0. 90 0. 60, 0. 55, 0. 50 



Width of genital segment 0. 70, 0. 83 0. 53, 0. 55, 0. 48 



Length of abdomen 0. 31, 0. 34 0. 41, 0. 37, 0. 33 



Length of caudal rami 0. 11, 0. 11 0. 13, 0. 11, 0. 10 

 Length of egg strings (neither female ovigerous) 



Description. — Female cephalothorax (fig. 49a) ovoid, consisting 

 of cephalon and fii"st 4 thoracic segments. Frontal region approxi- 

 mately one-thirteenth the greatest length of cephalothorax, Avith 

 fine membrane along anterior margin and pair of lunules overlapping 

 division between frontal region and remaining cephalothorax ven- 

 trally. Lateral margin of cephalothorax slightly irregular, A\dth fine 

 membrane projecting laterally and second membrane projecting med- 

 ially on ventral surface. Posterior lateral surface with small but 



