No. 5 meserve: monogenetic trematodes 61 



in mld-IIne. Eggs elongated oval, 0.096 to 0.136 mm. in length to 

 0.056 to 0.068 mm. in width, with extremely slender filiform polar 

 filament at one end of egg approximately one and one-half times 

 the length of egg. 



Comparisons. A. seriolae is most similar to A. heterocerca Goto, 

 1894, but is smaller (5.1 mm. to 7.5 mm. in length compared with 

 10.0 mm.), with twenty-seven to twenty-nine suckers on one side of 

 the haptor and thirty-eight to forty on the other as compared with 

 nine on one side and thirty on the other. The vitellaria are sepa- 

 rated along the entire length of the body as compared with the 

 posteriorly confluent vitellaria of A. heterocerca. 



A. seriolae is named after the genus of its host, Seriola. 



Axine elongata, new species 

 (Plate 8, figs. 53-58) 



Host: Xurel malampygus (Cuv. and Val.) 

 Location: Gills 



Locality: Secas Island, Panama 

 Number: 5 



Body long, slender, tapering slightly from posterior haptor to 

 anterior end which has a pronounced papilla-like structure at tip, 

 body 2.080 to 3.683 mm. in length by 0.288 to 0.531 mm. in greatest 

 width. Posterior haptor asymmetrical, 0.848 to 0.932 mm. in length 

 by 0.508 to 0.593 mm. in width, four to five suckers on short side, 

 twenty-four to twenty-five on long side. Posterior suckers slightly 

 longer than broad, 0.060 to 0.080 mm. in length by 0.048 to 0.080 

 in width. Chitinous skeleton (fig. 57) consists of a broad central 

 piece split down the center on one side with broadly bifurcating 

 ends, one side shorter than other; two pairs of lateral pieces uniting 

 at bases, one enlarged piece, blunt and slightly bifurcated at distal 

 end, other piece attenuated; a strong spine-like piece at base on 

 each side. Anterior sucker relatively small, wide apart, wider than 

 long, without membranous septa, 0.040 to 0.044 mm. in length by 

 0.036 to 0.060 mm. in width. Mouth ventral and subterminal. 

 Pharynx elongated, bulb-shaped, 0.040 to 0.044 mm. by 0.026 to 

 0.040 mm. in width. Intestinal limbs long, slender with lateral 

 branches, extend well into haptor region, left branch shorter than 

 right, ending blindly just in front of loop made by union of lateral 



