124 PROCEEDINGS OF THE NATIONAL MV8EVM. vol. f.O. 



Genus TRICHOSTRONGYLUS Looss, 1905. 



Synonyms. — Strongylus Mueller, 1780, of authors ; Tricostrongylus 

 Travassos, 19145. 



Generic diagnosis. — Trichostrong3^1inae (p. 123) : Small and 

 slender. Commonly reddish in color when first collected. Body 

 gradually attenuated forward from the genital aperture. Head small, 

 usually about 10 /x in diameter, with three small lips and with nodular 

 or punctiform papillae. Cuticle wdth annular striations. Cervical 

 papillae lacking. Buccal cavity not well differentiated. Esophagus 

 long, with simple well-developed dorsal gland. Nerve ring and ex- 

 cretory pore about 150 fi from the anterior end. Body of the cervical 

 glands behind the esophagus, one gland behind the other. Bursa 

 with large lateral lobes, without well-developed median lobe. Six 

 supporting rays in each lateral lobe. Ventral rays widely separated, 

 of very different thickness; the ventro- ventral is thin and directed 

 ventrally; the latero- ventral is thick and in close relation with the 

 lateral rays. Postero-lateral ray thinner than the other lateral rays, 

 and located close to the externo-dorsal ray. Dorsal ray short, cleft 

 at the end. Spicules short, spoon-shaped or spatula-shaped, and 

 presenting the appearance of being twisted, this appearance result- 

 ing from the arrangement of ridges on the spicules. The proximal 

 end of the spicule is thickened with a knoblike or disklike process 

 toward one side. Toward the j)osterior end of the spicule a more or 

 less prominent angular projection is usually present, giving the point 

 of the spicule a hooked or barbed appearance. Gubernaculum or ac- 

 cessory piece present, elongated and boat-shaped or shoe-shaped in 

 profile. Prebursal j^apillae small. Testis simple and not coiled. 

 Ovaries in older individuals slightly wavy, the anterior one disposed 

 in one or several loops. Uteri divergent. Ovijectors well developed. 

 Vulva in the posterior half of the body, slit-shaped or crescentic, sur- 

 rounded by somewhat protruding chitinous lips. Postanal portion of 

 the body of the female relatively short, with a pair of small caudal 

 papillae near the tip. Eggs of moderate size, thin shelled and color- 

 less, and containing a maximum of 8 to 32 segmentation cells when 

 oviposited. Parasitic in the duodenum, more rarely in the stomach, 

 of herbivores, rodents, and man. 



Type-species. — Trichostrongylus retortaeformis (Zeder, 1800) 

 Looss, 1905. 



ANALYTICAL KEY TO SPECIES OF TRICHOSTRONGYLUS. 



1. ilales less than 3 mm. long and female less than 5 mm. long. 



Trichostrongyliis fiberius, p. 129. 

 Males more than 3 mm. long and females more than 5 mm. long 2. 



2. Males over 7.5 nun. long; females over 10 mm. long; spicules over 500 fi 



long; vulva over 2 mm. from end of the tail; anus more than 150 fi and 

 less than 1 mm. from end of tail ; esophagus, testis, uterus, ovaries, and 

 eggs black Trichostrongylus pUjmervtatus, ij. 128. 



