434 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



elongate, 24 to 29 by 10 to 12 /x, usually about 25 by 10 fx. Excretory pore 

 subterminal and ventral ; branches of vesicle uniting dorsal to esophagus. 



The name gravidum refers to the extensive development of the uterus. 



Comparisons. This species is the third to be named in the genus. It 

 is more like T. lissosomum than like T. fustiforme. It differs from T. 

 lissosomum in smaller size, in extent of the uterus, in more compact pros- 

 tate gland, in unlobed posterior vitellarium, in shape of the seminal vesi- 

 cle, and in slightly smaller eggs. 



T. lissosomuTn and T. gravidum are both from Socorro Island, 

 Mexico, while T. fustiforme is from Florida. T. gravidum w^as not col- 

 lected from the Galapagos Islands. 



Aponurus trachinoti, new species 

 (Plate49, figs. 124, 125) 



Host: Trachinotus rhodopus (Gill) 



Location : Stomach 



Locality: Tenacatita Bay, Mexico 



Frequency : One specimen collected from one of hosts examined 



The single specimen is a typical member of the genus Aponurus, and 

 only a diagnosis is necessary for its characterization. 



DIAGNOSIS OF APONURUS TRACHINOTI 



The body is elongate, subcylindrical, 1.120 by 0.262; both ends 

 rounded and somewhat tapered, but forebody more tapered than hind- 

 body. Oral sucker 0.088; acetabulum 0.155; ratio not quite 1:2. Fore- 

 body (extended) 0.352 or almost Yz body length. Genital pore opposite 

 posterior half of pharynx. Pharynx 0.042 long, 0.051 wide. Esophagus 

 short; ceca extending only slightly beyond the vitellaria. Testes oblique 

 almost tandem a short distance posterior to acetabulum. Seminal vesicle 

 an elongate, almost straight tube, 0.102 in length; pars prostatica curved 

 dorsally in a bow; sinus sac pyriform, 0.093 long, 0.051 wide. Ovary 

 about in middle of hindbody ; vitellaria in a group of 4 and a group of 3 

 rounded masses; seminal receptacle medium sized, anterior to ovary, be- 

 tween ovary and posterior testis; uterus filling most of hindbody; eggs 

 pyriform, widest at or near one end, tapering almost to a point at the 

 other end, 25 fj. long, 10 /x greatest width. 



The specific name is for the host. 



Comparisons. This species of Aponurus is unique in the size and espe- 

 cially in the shape of the eggs. The eggs of A. sphaerolecithus are more 



