12 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.50. 



they force their way from the intermusculature connective tissue into 

 the sarcolemma. Here they show active movement and develop to 

 the infective larval state. They attain a length of 800 /a to 1 mm. 

 and a thiclmess of 30 /x and are found enrolled in a coil two to three 

 weeks after the infection. The anterior portion of the larvae is now 

 the thinner and more pointed, the posterior is thicker and rounded. 

 The sex organs are rudimentary, but the two sexes can be differen- 

 tiated. The larvae lie with the ventral surface toward the periphery 

 of the cyst; in the female the primordium of the genitalia may be 

 seen on the ventral side of the posterior portion of the esophagus; 

 while in the male the genital primordium is on the dorsal surface. 

 Farre's granules may also be seen in the female genitalia. These 

 larvae are at first free inside the sarcolemma, later encapsuled and 

 rolled in spirals, rings, or figures of eight. "Wlien the larval trichinae 

 from the muscles are ingested by a suitable animal, the capsule is 

 digested in the stomach and the larvae are set free. This may take 

 place in 24 hours. These larvae enter the intestine and in one to five 

 days become sexually mature. In three to four days after infec- 

 tion, the worms are found in copula. There are about 12 females to 

 each male. 



Hosts. — Epimys norvegicus {Mus decuTnanus) ., 31 us musculus^ Mus 

 albus^ Oryctolagus cuniculus {Lepus cuniculus), Lepus europaeus 

 {Lepus timidus), Cavia porcellus {Cavia cobaya)^ Cricetus cricetus 

 {Cricetus fnime7itarius) , and numerous hosts in groups of mammals 

 not covered in this paper. 



Location. — Small intestine. Larvae in musculature. 

 • Locality. — Cosmopolitan. 



TI4ICIIOSOM:Oir)IlSrA.E! Hall, 1916, rew subfamily. 



Suh family diagnosis. — Trichinellidae (p. 9): Males without 

 spicule or sheath and parasitic in the vagina or uterus of females; 

 eggs with opercular plug at each end and containing embryos when 

 oviposited. In urinary bladder, ureters, and pelvis of kidney. 



Type-genus. — Trichosomoides Eailliet, 1895. 



Genus TRICHOSOMOIDES Railliet, 189S. 



Synonyms. — Trlchosoma Rudolphi, 1819, of Bellingham, 1845, 

 TrichocepJudus Schrank, 1788, of Eberth, 18G3; Trichodes von Lin- 

 stow, 1874. 



Generic diagnosis. — Trichosomoidinae (p. 12) : With the char- 

 acters of the subfamily. 



Type-species. — Trichosomoides crassicauda (Bellingham, 1845) 

 Railliet, 1895. 



