C. L. Boulenger 
137 
de la ponte; l’embryon se developpe a l’interieur de la coque et 
y subit deux mues, apres quoi il est apte a rentrer directement 
dans l’organisme sans phase de liberte dans le milieu exterieur. 
Habitat: ordinairement le duodenum des Ruminants. 
Railliet and Henry also show that there has been in the past consider¬ 
able confusion between the two species N. filicollis and N. spathiger, 
and point out that whilst Schneider (1860) correctly figured the true 
N. filicollis Rud., the specimens described under that name by Curtice 
(1890), Stodter (1901), and Ransom (1911) are to be referred to N. 
spathiger Railliet. 
Maupas and Seurat recently (1912) described N. filicollis from the 
dromedary and sheep in Algeria; from the descriptions given by the 
authors there can be little doubt that these worms are also to be included 
in Railliet’s N. spathiger 1 . 
On account of this confusion between the two species I have con¬ 
sidered it advisable to give a short description of the adult individuals 
observed by me in England before proceeding to the account of their 
development; it will be seen that these worms belong to the true 
Nematodirus filicollis Rud. as defined by Railliet and Henry. 
Specific Diagnosis. 
In the adults the body is slender and considerably attenuated 
anteriorly; the living worms are semi-transparent and either colourless 
or, more frequently, tinged with a blood-red colouring matter, the latter 
often most intense at the anterior and posterior extremities and appar¬ 
ently lying in the body-cavity and not in the alimentary canal. The 
cuticle is nearly always inflated at the anterior extremity, and in the 
region of the neck is marked with transverse striations, absent from 
the rest of the body, which is provided with eighteen longitudinal 
cuticular lines. The head has a breadth of 30 to 60/x and bears six 
small papillae surrounding the circular mouth. Cervical papillae are 
absent. The oesophagus measures 450-600p, in length and is broadest 
posteriorly (30-40/z). The nerve-ring is situated about 300/x from the 
anterior extremity, the excretory pore 50-70p in front of the junction 
of oesophagus and intestine. 
Male. The average length of the male was found to be 1T5 mm., 
the smallest mature specimen measured 7-5 mm., the largest 13-5 mm. 
1 Seurat has recently (1913) described the Rodent Ctenodactylus gundi as a host of 
Nematodirus filicollis in Tunisia. The figures of the worms given by the author show 
that these also do not belong to this species. 
