No. 5 meserve: monogenetic trematodes 69 



v/ith the atrium and one with the cirrus, are characteristic of the 

 genus. 



Discussion. The shape, size, and arrangement of posterior suck- 

 ers of Cestracolpa is similar to Axine. The genus differs from Axine 

 principally in that it has a lateral vaginal opening with a conspicuous 

 spine imbedded in the wall at distal end of vaginal canal and pro- 

 truding from the vaginal orifice. 



The name Cestracolpa is from cestra, dart, and colpa, vagina, 

 referring to the spine in the vagina. 



Cestracolpa yamagutii, new species 



(Plate 10, figs. 81-85) 



Host: Unidentified flying fish 



Location: Gills 



Localities: Clarion Island, Mexico, and open sea off 



coast of Mexico 

 Number: 2 



Body 7.323 to 7.886 mm. in length by L732 to 1.733 mm. at 

 greatest width, divided into three portions, a slender, attenuated 

 part anterior to vaginal opening, a broad middle part which tapers 

 slightly from middle of body to level slightly anterior to haptor and 

 the short broad region bearing haptor. Posterior haptor with con- 

 cave border on right side, L168 to L169 mm. in width. Posterior 

 suckers small, seventy-five in number, four times as wide as long, 

 0.020 mm. in length by 0.080 mm. in width. Chitinous skeleton (fig. 

 84) of suckers consists of a very wide, short piece in center bifur- 

 cated at both ends; two pairs of relatively short and slender pieces 

 imbedded in lateral walls of sucker; twenty-four short, almost 

 straight pieces imbedded in base of sucker, twelve on each side; 

 and two pieces across top with convex borders directed distally. 

 Mouth subterminal, ventral, almost at extreme end. Pharynx rela- 

 tively small, bulb-shaped, 0.044 mm. in length by 0.036 to 0.044 mm. 

 in width. Esophagus long, relatively wide, in mid-line, bifurcating 

 just anterior to level of vaginal opening. Anterior suckers small, 

 elliptical, longer than broad without membranous septa, 0.060 to 

 0.064 mm. in length by 0.032 mm. in width. Intestinal limbs with 

 lateral branches, not united posteriorly. Testes large, smooth, broader 

 than long, in two rows, fifty-two in number. Vas deferens slender. 



