NECTURUS MACULATUS. 42] 
anterior ends, a union which, in a macerated skull, often holds long after the separation of 
the other components of the jaw. The recurved ventral margin of the dentale becomes 
closely applied upon the inner side of the mandible to the corresponding edge of the 
angulare and usually completes the formation of the intermandibular foramen. The 
spleniale comes in contact with it by a portion of its outer surface. 
2. ANGULARE. This bone is a curved splint, broad behind and tapering anteriorly 
into an extremely fine and sharp point. Its outer aspect is concaved to receive Meckel’s 
cartilage, and this surface, together with the inner surface of the dentale, forms a nearly 
complete canal for the protection of the cartilage just named. The most solid portion of 
the bone is that which forms its 
lower margin, and this part, when Outer Aspect 
articulated with the dentale, forms 
a direct continuation of the flat sub- 
mental surface of the latter. Poste- 
riorly it ends in a blunt, rounded, gk 
angular process which furnishes at- 
tachment to the digastric muscle. 
Along the external aspect of this 
heavy portion there run a sharp 
edge for articulation with the ven- 
tral edge of the dentale, and in this, 
at about its posterior third, is either 
a deep notch or a complete fora- 
For mandib 
men, the former being much the : 
Groove sor 
more usual. This is reinforced by neckesicars tags 
the edge of the dentale and forms Inwen Aspect 
the mandibular foramen, through Fig. 20. Two views of right angulare. Xx 3. Contact surfaces 
- . 5 with other bones are designated by an x. 
which the mylo-hyoid branch of the 
fifth nerve reaches the intermandib- 
ular region. The remaining, or dorsal part of the bone forms a flattened and much 
curved wing ending in a sharp upper edge, the rounding outline of which forms a coro- 
noid process which receives the insertion of the temporalis muscle. Along the anterior 
slope of this process the upper margin is applied to the lower margin of the spleniale. 
This bone is easily oriented, since the more solid base is ventral and the slight curve 
of the main axis follows the curve of the jaw. 
3. SPLENIALE. Next to the operculum of the otic capsule, this is the smallest bone 
of the skull, and by a singular coincidence, many authors have given it the name “ oper- 
