108 PROCEEDINGS OP THE NATIONAL MUSEUM. vol. 50. 



dorsal rays originate in a common trunk, the dorsal ray ending in 

 tridigitate terminations. The vulva in the posterior third of the 

 body and the uteri divergent. 



Type-genus. — Strongylus Mueller, 1780, 



ANAI-YTICAL KEY TO GKNEKA OF STKONGYLEAE. * 



1. No corona radiata ; buccal capsule opens dorsally Uncinaria, p. 111. 



Corona radiata present; buccal capsule does not open dorsally 2. 



2. Posterior two-thirds of buccal capsule covered with round knobs. 



Tracliypharyyix, p. 109. 

 Buccal capsule without a covering of knobs Strongylus, p. 108. 



Genus STRONGYLUS Mueller, 1780. 



Synonyms. — Strong'dus Eudolphi, 1801 ; Sclerostonia Eudolphi, 

 1809; Sclerostomum Dujardin, 1815; Sdorostovrhum Sonsino, 1878; 

 Steongylus Giles, 1892. 



Generic diagnosis. — Strongyleae (p. 107) : Anterior extremit}^ trun- 

 cated, straight or slightly curved toward the ventral surface. The 

 open, circular mouth, transverse or oblique, is followed by a chitinous 

 buccal capsule and the edge of the mouth is furnished with one or 

 several series of numerous denticles, the corona radiata. The two 

 equal spicules are long and slender. The bursa is trilobed. The 

 ventro-ventral and latero-ventral rays are parallel, close together 

 and have a common origin. The externo-lateral, medio-lateral, and 

 postero-lateral rays originate in a common trunk and proceed in 

 slightly diverging lines; they are of much the same shape, all taper- 

 ing somewhat from the base. The dorsal and externo-dorsal rays 

 originate in a common trunk, the latter originating near the base of 

 the common trunk and occupying a relatively independent position. 

 The main stem of the dorsal ray divides to form the two terminal 

 dorsal rays, and each of these gives off an external branch and then 

 forks again distally to form two terminal branches. One of the three 

 branches of the dorsal rays may be missing. Vulva in the posterior 

 third of the body. Uteri divergent. 



Type-species. — Strongylus equlnus Mueller, 1780. 



ANATA'TICAL KEY TO SPECIES OF STKONGYLUS. 



1. Undescribed species Stronpylus species, p. 109. 



Described species :^___»s'//-o»;////».s isotrichis, p. 108. 



STRONGYLUS ISOTRICHIS (Molin, i86ol() Hall, 1916. 



Synonytn. — Sclerostomum isotrichis Molin, 1860/>. 



Specific diagnosis. — Strongylus (p. 108) : Head continuous with 

 body. ISIouth acetabular in shape, the internal margin with vertical 

 walls and the large circular aperture with a diaphanous border 



