Sderostomes of the Horse 
Genus Triodontophorus Looss 1901. 
Triodontus Looss 1900, non Westwood 1845. 
Triodontoporus Railliet and Henry 1902. 
The genus Triodontophorus was established by Looss (1901) to 
include two very characteristic Sderostomes met with in Egypt, in 
which the oral capsule contained three peculiarly arranged teeth arising 
from its floor and directed towards the mouth opening. Two species, 
T. serratus and T. minor, were obtained from horses and donkeys. 
Railliet and Henry (1902) announced the discovery of the genus in 
France, but do not seem to have identified the species observed by 
them. T. serratus was later recorded by v. Linstow (1904) and Leiper 
(1910) from horses in India and England respectively. 
A third species, T. intermedins, was described by Sweet (1909) 
from the horse in Victoria, Australia. 
In addition to these three forms from the Equidae, a fourth species, 
T. deminutus, has been described from man in the tropics by Railliet 
and Henry (1905); these authors were able to show later (1909, 1912) 
that, in spite of certain superficial resemblances, especially in the 
structure of the oral capsule, to Looss’ genus, this form belongs to a 
distinct genus, named by them Ternidens ; it is more closely related to 
the Oesophagostomeae than to the Cylicostomeae in which Triodonto¬ 
phorus is included. 
The section Cylicostomeae of the sub-family Strongylinae 1 (Sclero- 
stominae) is defined by Railliet and Henry (1912) as follows: 
“Bourse caudale a cotes anterieures fendues, moyennes dedoublees, 
posterieures externes naissant isolement, posterieures tridigitees. 
Vulve proche de 1’anus; uterus a branches paralleles. Parasites du 
tube digestif.” 
Three species of Triodontophorus were found in horses in the 
Birmingham district, of which none could be assigned to either of Looss’ 
species; one species is referred to T. intermedins Sweet, the two others 
are described as new. 
The genus Triodontophorus can be defined as follows: 
Cylicostomeae: Cuticle transversely striated. Mouth capsule large, 
with three radially-arranged teeth projecting forward into its cavity 
1 Railliet and Henry (1912) give the following definition of this sub-family of the 
Strongylidae: “Capsule buccale bien developpee. (Eufs en segmentation au moment 
de la ponte. Presque toujours embryon rhabditiforme et developpement direct.” 
