SKULL OF A HUMAN FETUS OF 40 MM. 417 



from the nasal bone, and almost touches its neighbor of the 

 opposite side, this being the part of the bone which most nearly 

 reaches the median plane. Posteriorly it gradually recedes 

 from this plane, the entire medial edge of the horizontal portion 

 underlying the outward-slanting ventro-lateral edge of the 

 sphenoethmoidal cartilage. Its dorsal extremity is separated by 

 a considerable interval from the parietal bone. It also, for tech- 

 nical reasons, is figured as a plate. 



The squamosal (figs. 2, 4 and 13) is a somewhat fan-shaped 

 bone, in which two distinct portions may be recognized; a pos- 

 terior flattened plate, covering laterally the auditory ossicles and 

 the upper part of Meckel's cartilage, and a ventral, elongated 

 spicule of bone, the zygomatic process, whose tip is found just 

 above the dorsal tip of the zygomatic bone. The upper edge of 

 the flattened portion is convex upward, and is somewhat ser- 

 rated, the lower border being slightly concave, and passing 

 directly into the zygomatic process. The latter, owing to its 

 lying parallel with the sagittal plane, meets the flattened portion 

 at an angle, as the latter looks outward and forward (fig. 2). 



The zygomatic bone (figs. 2 and 4) is somewhat quadrilateral 

 in shape, and thus bears a resemblance to its adult condition. 

 It already shows a body, with four angles, three of which termi- 

 nate in marked projections. The body is flattened and thin, 

 and the ventral part of its medial surface is in close apposition, 

 though not in union, with the zygomatic process of the maxiUa. 

 From the dorso-caudal angle there projects backward a spicule 

 of bone, whose dorsal extremity, underlies the ventral extremity 

 of the zygomatic process of the squamosal, thus identifying it 

 with the zygomatic process of the zygomatic bone; the zygomatic 

 arch is, accordingly, incomplete. From the cranial angle there 

 projects upward and slightly backward the rather blunt, but 

 strongly marked, frontal process, lying somewhat ventro-lateral 

 to the upper extremity of the ala temporalis, and a slender 

 elongated and inwardly curved infra-orbital process overlies the 

 outer border of the zygomatic process of the maxilla. The 

 caudo-ventral angle of the body is well-marked, and represents 

 the anlage of the future malar* tubercle. 



