ACANTHOCEPHALA 79 
Arhythmorhynchus teres, ew species. 
Body of preserved specimen about 43 mm. long with a diameter of 0,75 
mm. near anterior extremity. Remainder of body varying somewhat in dia- 
meter in different regions but about 0,3 mm. broad. Posterior region swollen 
to a diameter of about 0,68 mm. and bluntly truncated at termination. Pro- 
boscis 0,77 mm. long, slightly ditated (0,325 mm. across) at the middle and 
of smaller diameter (0,23 mm.) at tip and base. Proboscis hooks in 18 longi- 
tudinal rows of about 14 to 16 hooks each. Hooks not differing much in 
length but in different parts of proboscis varying widely in contour and in 
thickness, usually about 60 », long; those near base very slightly curved and 
delicate, while those near the middle of proboscis in some instances have a 
diameter of 18 », at the point of emergence from proboscis wall. 
Habitat: intestine of Larus dominicanus at Talcahuano, Chile. Collected 
November 22, 1916 by Mr. K. BACKSTROM. 
Type deposited in the Riksmuseum in Stockholm. 
Literature Cited. 
Ltue, M., 1911. Acanthocephalen. Die Siisswasserfauna Deutschlands, Heft 16. Jena. 
——, 1912. Zur Kenntnis der Acanthocephalen. Zool. Jahrb., Jena, Suppl. 15, 
Bader: 271-306. 
Neveu-Lemarre, M., 1905. Sur les Parasites des Poissons du Genre Orestias. Bull. 
Soc. Philomathique de Paris, ‘ome 7: 255—259. 
Van Crieave, H. J., 1918. Acanthocephala of the subfamily Rhadinorhynchinae 
from American fish. Jour. Parasitol., 5: 17—24. 
——, 1920. ‘Two new genera and species of Acanthocephalous worms from Vene- 
’ 
zuelan fishes. Proc. U. S. Natl. Museum, 58: 455—4066. 

