NO. 2131. NEMATODE PARjL'^lTEi^ OF RODENTS— HALL. 107 



of a rliabditiform embryo in the Strongylidae and its absence in 

 the Metastrongylidae, as divided by Railliet and Henry, is a feature 

 that points to ancestral differences of importance. The writer has 

 followed Travassos (1914Z>) in treating all three groups as of coordi- 

 nate family rank. 



Family STRONGYLIDAE Cobbold, lSo4. 



Familij diagnosis. — Strongyloidea (p. 100) : Meromyarian. Buccal 

 capsule present. Bursa highly developed, with a typical system 

 of supporting rays consisting of one or two dorsal rays and two 

 lateral ra}^ systems of six rays each. Male with two spicules and 

 female with two ovaries. Vulva at times anterior of the middle 

 of the body, but usually posterior of the middle. Oviparous, eggs 

 segmenting when laid. Development, so far as known, direct. Em- 

 bryo rliabditiform. In digestive, rarely in respiratory, system. 



Type-genus. — Strongylus J^lueller, 1780. 



Subfanaily STKOnSTG-YLINV^E Railliet, 1803. 



Subfamily diagnosis, — Strongylidae (p. 107) : Meromyarian, Buc- 

 cal capsule present. In digestive, occasionally in respiratory, system. 

 Development direct, at times complex, involving cutaneous infection, 

 nodular development or other embryonic or larval migration. 



Type-genus. — Stro7ig ylus IMueller, 1780. 



ANALYTICAL KEY TO TRIBES OF STEONGYLINAE. 



1. No description Trilje iincei-taiu, p. 121. 



Ilecognizuble forms 2. 



2. Dorsal and latero-dorsal rays originate separately, the dorsal triiulc ending in 



4 digitations ; vulva close to anus and uteri divergent Ransomeae, p. 115. 



Dorsal and latero-dorsal rays originate in a common trunk, or if separately, 

 thei'e are 2 dorsal branches with 3 digitations ; vulva close to anus and 

 uteri convergent, or vulva remote from anus and uteri divergent 3. 



3. Dorsal and externo-dorsal rays originate separately ; vulva close to anus and 



uteri convergent Cylicostomeae, p. 114. 



Dorsal and externo-dorsal rays originate in a conmion trunk ; vulva remote 

 from anus and uteri divergent 4. 



4. Dorsal ray tridigitate ; vulva in posterior third of body Strongyleae, p. 107. 



Dorsal ray bifurcate; vulva in middle or anterior portion of body. 



Bunostomeae, p. 112. 



Tribe STRONGYLEAE Railliet and Henry, 1912ff. 



Synonym. — Ankylostomeae Eailliet and Henry, 1909^. 



Trihe diagnosis. — Strongylinae (p. 107) : Ventro- ventral and latero- 

 ventral raj^s close together and parallel. Medio-lateral and postero- 

 lateral rays not close together and parallel. Dorsal and externo- 



