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Classification of the Ascaridae 
J he first group consists of forms in which the uterus is of the primitive two- 
branched type, but with the vulva usually situated in the posterior region of 
the body, and rarefy in front of the middle, its more usual position among the 
Ascarinae. These forms are further characterised by the presence of more or 
less well-developed interlabia between the main lips, and usually by having the 
cuticle at the bases of the main lips deeply grooved by an incision running in 
from the interlabium on either side. 
The second group consists of species in which the uterus breaks up into 
more than two (four or six) branches, the vulva is situated, with few exceptions, 
in front of the middle of the body, and interlabia are absent. One species not 
from a snake, but from a chamaeleon, is included in this group. 
Among the characters common to all, or most, of the species comprised in both 
gioups are the general form of the spicules of the male, which have a tubular 
shaft and two broad membranous alae; the presence of simple dentigerous 
ridges on the inner surfaces of the lips; and the character of the ova, which are 
in all cases large, nearly spherical or of a much rounded oval shape, with a thick 
shell ornamented with granulations externally, and with the contents only 
segmenting at the time of laying. A further character which is not improbably 
universal is the presence of series of radiating digitiform processes on the 
anterior borders of the pulps of the lips. These processes are sometimes obvious 
in some specimens and hard to detect in others of the same species, and their 
visibility or otherwise evidently depends to a large extent on the state of 
preservation of the material and the technique employed in its examination. 
It is difficult, therefore, to make use of this character for systematic purposes. 
The two main groups already referred to, and their component species, 
may now be diagnosed. 
(1) Ophidascaris, n.g. 
Generic Diagnosis. Ascarinae : Lips almost square, with more or less 
rounded angles, and generally as broad as long. Dorsal lip slightly smaller 
than ventro-lateral lips. Interlabia usually well-developed. From the inter- 
labia deep transverse grooves in the cuticle run partially round the bases of the 
main lips towards their main axes. Oesophagus relatively short, without bulb 
01 ventriculus. No oesophageal or intestinal caeca (the intestine, however, is 
frequently pushed up into an annular “caecum round the posterior end of the 
oesophagus). Vagina and uterus run backwards from the vulva. Uterus with 
two parallel branches. Vulva usually behind middle of body, and genital 
organs (in both sexes) usually confined to the posterior region of the body, 
which often shows a fusiform thickening. 
Genotype: O.filaria (Dujardin, 1845). 
