The portion of the lachrymal duct communicating with the cavity of the nose has, on the other hand, been abnormally developed, apparently for the purpose of cleansing that chamber from particles of sand which may obtain an entrance while the animal is burrowing.
A glandular streak extending from the nostril towards the eye is the lachrymal canal.
Vittatus, of Sumatra, characterized by having a broad reddish or whitish band running from the middle of the snout along the upper lip to disappear on the side of the neck; the skull being short and high, with the facial portion of the lachrymal bone small.
The lachrymal forj amen is always within the orbital margin; and in many species the infra-orbital foramen is very large (in some as large as the orbit) and transmits part of the masseter muscle.
X P11,1x, premaxilla; Mx, maxilla; Ma, malar; Fr, frontal; L, lachrymal; Pa, parietal; Na, nasal; Sq, squamosal; Ty, tympanic; ExO, exoccipital; AS, alisphenoid; OS, orbito-sphenoid; Per, mastoid bulla.
The lachrymal foramen in the skull is low down and forms an elongated slit.
In the skull the lachrymal bone is large, the paroccipital process is directed vertically downwards and the tympanic bulla is hollow.
The jugal is without an inferior angle, and extends forwards to the lachrymal; the palate is contracted in front and deeply emarginate behind; the incisors are short, and the molars divided by continuous folds into transverse plates; and the two halves of the lower jaw are welded together in front.
The three remaining families of the Hystricoidea, of which one is African while the other two are chiefly South American, are very closely allied and often brigaded in a single family group. In the Capromyidae, which includes only the South American and West Indian hutias, the South American coypu and the African cane-rats, the tympanic bulla of the skull is hollow, the par-occipital process straight, the lachrymal small, and the cheekteeth rooted, with deep enamel-folds; the first front toe Leing occasionally absent.
In the skull there are two orifices to the lachrymal duct, situated on or inside the rim of the orbit.
A preorbital vacuity of such dimensions as to exclude the lachrymal bone from articulation with the nasal.
Usually only one orifice to the lachrymal canal, situated inside the rim of the orbit.
Lachrymal bone almost always articulating with the nasal.