PAEASITES OF GALVESTON BAY FISHES CHANDLER 151 



Class ACANTHOCEPHALA 

 Family NEOECHINORHYNCHIDAE Travassos, 1917 



ATACTORHYNCHUS, new genus 



Geneno diagnosis. — Body small, stout, veiitrally curved, with 

 greatest diameter behind middle. Proboscis very small, armed with 

 about eight diagonally transverse rows of hooks, about eight in num- 

 ber in anterior rows, about twice as many and half as large in 

 posterior rows, the arrangement strikingly irregular. Hooks U- 

 shaped, with large rod-shaped roots and slender spines, only tips of 

 which project through cuticle. Proboscis sac about twice as long as 

 proboscis. Retractor muscles of proboscis sac attached behind mid- 

 dle of body. Lemnisci very long and large, extending about to 

 middle of body, one containing one nucleus, the other two. Testes 

 large, subglobular, contiguous; syncytial cement gland in contact 

 with testes. Well-developed cement reservoir and seminal vesicle, 

 the latter with two ducts. 



Type species. — Atactorhynchus verecundus, new species. 



Remarks. — The only other genera in the family Neoechinorhyn- 

 chidae with more than four horizontal rows of hooks on the pro- 

 boscis are T anaorhamphus Ward, 1918, and Pandosentis Van Cleave, 

 1920. T anaoThampKus has a large, elongate proboscis with 20 or 

 more transverse rows of large hooks, and a body that is cylindrical 

 or enlarged anteriorly, while Pandosentis has a short cylindrical 

 proboscis with hooks that are not U-shaped but bent at right angles, 

 remarkablj^ short lemnisci, and short retractor muscles. 



ATACTORHYNCHUS VERECUNDUS, new species 



Plate 12, Figures 5-7 



Specific diagnosis. — Body robust, bluntly rounded posteriorly, 

 tapering to small proboscis anteriorly, and with maximum diameter 

 behind middle of bod5\ Females up to 6.5 mm in length, with 

 maximum diameter about 0.63 mm. Males up to 4.5 long, usually 

 smaller, with maximum diameter of 0.6 mm or less. Proboscis very 

 small, nearly cylindrical, but slightly expanded distally, about 0.15 

 mm long and 0.06 mm in diameter. Hooks arranged irregularly in 

 • about eight diagonally transverse rows, the first four or five of 

 which, occupying anterior two-thirds of proboscis, with about eight 

 hooks each; last two or three rows smaller and with more hooks, 

 last row having about 16, which are about half the size of anterior 

 hooks. Hooks U-shaped, with broad, bluntly rounded roots and 

 slender sharp points, only tips of which project through cuticle. 



