NO. 15 VAN CLEAVE : ACANTHOCEPH ALA 503 



Generic diagnosis. The genus Gorgorhynchus includes species para- 

 sitic in marine fishes. Body elongate and usually slender, somewhat 

 expanded anteriorly. Body spines in a single field at the anterior extremity 

 of the body. Proboscis cjdindrical or barrel shaped, relatively stout, 

 densely armed with numerous hooks arranged in quincunxial order of 

 alternating longitudinal and circular rows not showing profound regional 

 or dorsoventral differentiation. Proboscis receptacle double walled with 

 the brain well forward toward its anterior end. Lemnisci long, slender. 

 Male genitalia occupy more than the posterior half of the body with the 

 testes just posterior to the widest part of the body. Testes usually 

 separated some distance and followed by four extremely long, tubular 

 cement glands. 



Type species. Gorgorhynchus medius (Linton, 1907). 



Gorgorhynchus lepidus, new species 

 (Plate 51, figs. 1-5) 



Host: Cratinus agassizii Steindachner, Tagus Cove, Albemarle 

 Island, Galapagos, January 14, 1934. 



Types. Eleven specimens (5 males and 6 females). Holotype male 

 (VC 3126.6) and allotype female (VC 3126.7) and series of paratypes 

 in the Allan Hancock Foundation of The University of Southern Cali- 

 fornia. Paratypes also deposited in the collection of H. J. Van Cleave, 

 Urbana, Illinois, and of the U.S. National Museum. 



Specific diagnosis. No fully mature individuals available. Body of 

 immature specimens 7 to 10 mm long with greatest diameter (0.8 to 

 0.9 mm) posterior to the tip of the proboscis receptacle. Posterior region 

 of body much reduced in diameter (about 0.4 mm). Anterior region 

 of body closely set with spines in a single continuous field which on the 

 ventral surface extend from one half to three fourths the length of the 

 receptacle but on the dorsal surface from one fourth to one half the 

 length of the receptacle. Spines 65 to 90 /x long, often with a root process 

 extending anteriorly from the base of the spine. Proboscis large, somewhat 

 barrel shaped with greatest diameter (0.46 to 0.5 mm) near the 

 middle tapering slightly toward each end; 1.6 to 0.8 mm long, 

 armed with 20 longitudinal rows of 14 to 16 hooks each. Near middle 

 of proboscis the ventral hooks are 106 to 120 jx long, dorsal hooks in 

 corresponding location 96 to 118 /x long; those on ventral surface usually 

 much heavier. Proboscis receptacle 1.7 to 2.2 mm long with the brain 



