No. 5 meserve: monogenetic trematodes 59 



than long, without membranous septa, 0.024 to 0.036 mm. in length 

 by 0.056 to 0.064 mm. in width. Pharynx bulb-shaped, 0.024 to 

 0.032 mm. in length by 0.022 to 0.029 mm. in width. Esophagus 

 slender, bifurcating in region of genital pore. Intestinal limbs with 

 lateral branches, not united behind. Genital pore well forward 0.120 

 to 0.169 mm. from anterior end. Genital hooks in two rows on each 

 side, one row dorsal to the other, dorsal hooks shorter; long ventral 

 hooks 0.016 to 0.020 mm. in length, almost straight, wider at proxi- 

 mal end with recurved points pointing posteriorly into genital pore. 

 Short hooks a little over one half length of long hooks. Twenty- 

 eight to thirty-nine testes in two rows posterior to ovary, smooth, 

 wider than long, unlobed. Ovary in shape of interrogation point, 

 anterior part expanded and posterior part with small lobe which is 

 bent to left, in middle of body in mid-line, greatest diameter 0.056 

 to 0.076 mm. Seminal receptacle elliptical, to right of ovary. Vitellaria 

 from genital pore to one half distance from testes to posterior end. 

 No eggs present. Brain with two projecting anterior lobes with short 

 lateral projections on each side. 



Comparisons. The two main features which distinguish A. 

 oligoplitis from others previously described are the hooks of the 

 genital pore which are arranged in two parallel groups on each side 

 of the genital pore and the brain which has two small extra lobes 

 arising anteriorly from the brain proper. These accessory anterior 

 lobes have small lateral extensions which arise lateral and at right 

 angles to them. It is most like /^. aberrans Goto but is somewhat 

 smaller (1.8 to 1.9 as compared with 5.0 mm.). A. aberrans has 

 twenty-five suckers on one side and only one on the other as com- 

 pared with sixteen to eighteen suckers on one side and forty to 

 forty-two on the other in A. oligoplitis. 



A. oligoplitis is named after the genus of the host, Oligoplites. 



Axine seriolae, new species 

 (Plate 8, figs. 48-52) 



Host: Seriola dorsalis (Gill) 



Location: Gills 



Locality: Hood Island, Galapagos Islands 



Number: 4 



Body elongated triangular, slightly curved to right with greatest 

 width at level of ovary, tapering gradually to anterior end of vitel- 



