58 PROFESSOR OWEN ON THE AYE-AYE. 
on the front and sides of the neck, and extending upon the sides of the deep man- 
dibular rami. ; 
The sterno-cleido-mastoideus consists of two portions, which are more than usually 
distinct to their insertions. The sternal portion (ib. »), commencing by a short roundish 
tendon from the outer angle of the manubrium, becoming fleshy, expands to the breadth 
of five lines, is flat, and covers the cleidal portion (:’), arising fleshy from the median third 
of the clavicle. The sternal portion is inserted into the mastoid, and the ridge con- 
tinued thence upon the occiput. The cleidal portion contracts to its insertion, which 
is tendinous, at the back of the mastoid. The two portions are continuous along the 
front margin, and separate behind, the sternal overlapping the other. 
The omo-hyoideus arises fleshy from the upper costa of the scapula, and passes 
obliquely upward and forward, crossing the carotid artery, becoming flattened, with 
a breadth there of three lines,.to be inserted into the hyoid, along with the sterno- 
hyoideus, and to the aponeurosis connecting the beginning of the tendon of the diga- 
stricus to the hyoid. 
The anterior bellies of the pair of digastrici muscles are closely blended together, and 
fill up the anterior interspace of the rami of the lower jaw. The tendon of each diga- 
stricus, commencing at the hyoid, is about five lines in length; the posterior belly 
consists of two fasciculi of muscular fibres, and arises from the lower part of the 
mastoid. 
The sterno-hyoidei, each five lines in breadth at their origin, gradually contract as 
they ascend towards their insertion, and are closely connected at the middle line, 
covering the larynx and trachea. 
The sterno-thyroidei are much smaller muscles ; they arise behind and externally to 
the sterno-hyoidei, and pass along the side of the trachea, to be inserted below the 
thyro-hyoideus into the thyroid cartilage. 
The longus colli is a powerful muscle, especially thick at the part which is attached 
to the pleurapophyses of the sixth and fifth cervicals. 
twice the extent that it does on the inner ; it is naked, except just at its edge, where it is slightly overlapped by 
crusta petrosa, which extends up to the worn part of the tooth, and covers all the dentine which is not protected 
by enamel. The crusta petrosa at the part of the incisor examined (its distal extremity) is very thin, and only 
a transparent layer, without lacunee. The pulp-cavity was sealed by an exceedingly thin layer of secondary 
dentine, so thin that the vessels of the pulp reached within less than a line of the surface. The point where the 
section was made exposed the vascular pulp. In the molar tooth the bulk of the crown is composed of enamel, 
which is bare,—not covered, that is, by crusta petrosa. 
“Tt can scarcely be said that the teeth present any histological characters of marked peculiarity. If, however, 
one thing is more noticeable than another (especially in my incisor section), it is the large number of dentinal 
tubes which enter the enamel, as is conspicuous in marsupials. This, however, is an inconstant structural con- 
dition ; it is found in many mammalian teeth, differing in individuals of the same species, and also in different 
teeth of the same individual, and is not of the zoological value that has been imagined. I should, therefore, 
attach very little importance to the circumstance as seen in a single specimen only.”’—J. 8. 
