152 PROCEEDINGS OF THE NATIONAL MUSEUM vol.83 



Measured from top of bend both x^oints and roots about 18ju to 19/a 

 long in hooks at anterior end of proboscis and only 9/a to lO/x long 

 in hooks of posterior row. Proboscis sac about twice length of 

 proboscis. Retractor muscles of sac long and slender, attached pos- 

 terior to middle of body, so anterior end of body can be, and fre- 

 quently is, retracted. Lemnisci long, about half length of body, in 

 males terminating at about anterior margin of anterior testis. 

 Testes in posterior half of body, contiguous, 300/t to 400/x long and 

 about two-thirds as wide. Syncytial cement gland just behind 

 testes, sometimes smaller, sometimes larger, in size; number of 

 nuclei not determined. Cement reservoir bag-shaped, just behind 

 cement gland. Seminal vesicle rounded, dorsal to anterior end of 

 cement reservoir, and connected with genital aperture by two ducts. 

 Eggs in uterus of female 27/x to 30/* long and 12/a to 13ju, broad. 



Host. — Cyprin odon vanegatus. 



Location. — Intestine. 



Locality. — Galveston Bay, Tex. 



Type specime7i. — U.S.N.M. Helm. Coll. no. 39549; paratypes, no. 

 39550. 



Remarks — This parasite was found in about 30 to 40 percent of the 

 specimens of Cyprinodon variegatus taken in the upper parts of 

 Galveston Bay in August and was present in fairly large numbers in 

 some hosts. Eighteen specimens of this fish taken on Galveston 

 Island early in March yielded only two female worms, one in each 

 of two hosts. 



Family CENTRORHYNCHIDAE Van Cleave, 1916 



ARHYTHMORHYNCHUS DUOCINCTUS, new species 



Plate 12, Figuees 8, 9 



Speci-fic diagnosis. — Salmon colored when living, body spindle- 

 shaped, quite abruptly narrowed posteriorly, 3.2 to 4.2 mm in length, 

 with maximum diameter of 0.77 to 1.05 mm. Proboscis spindle- 

 shaped, 685/A to 900/i long, 160/i to 200/x in diameter anteriorly, 

 285/A to 310/i through bulged region, 200/i to 240/x at base. Proboscis 

 hooks arranged in 18 or 19 longitudinal rows of 15 or 16 hooks each. 

 Anterior hooks moderately slender, sharply bent at base, blade nearly 

 straight, 53/x long and 13ju, to 15/* in diameter; hooks on bulged area 

 shorter and heavier, more evenly curved, 47/i long and 19/t in diam- 

 eter; posterior hooks slenderer, gentl}^ curved, 50/x long and 8/* to 

 lO/i in diameter. Neck imarmed, in form of trimcated cone, 360/i to 

 400/t long. Anterior part of body with two bands or girdles with 

 fine transverse striations, and armed with spines in fairly regular 

 quincunxial arrangement; anterior band shortly behind neck, with 



