SKULL OF A HUMAN FETUS OF 40 MM. 341 



immediately dorsal to the otic capsule, and is separated there- 

 from by the cranial portion of the lateral capsulooccipital groove. 

 Its posterior part projects slightly into the cranial cavity (fig. 5), 

 and its edges are ill-defined, fading gradually into the surround- 

 ing cartilage. This marks the thickest part of the squama. It 

 may be followed caudally as a low ridge on the outer surface, 

 and is seen to meet, almost at a right angle, a second ridge, which 

 extends from the tip of the paracondyloid process to the dorsal 

 foraminal prominence, and to which the name crescentic ridge 

 (figs. 2-3) may be given, the point of union being about the 

 center of the latter. 



The crescentic ridge, seen only on the outer surface of the skull, 

 is a low elevation which sweeps dorsally and medially, between 

 the extremities above mentioned, and in so doing describes a 

 curve with convexity backwards and outwards. At its ventral 

 end it is sharply defined, and is separated from the ear capsule 

 by the small notch which stretches outward from the jugular 

 foramen. Dorsally it is wider, and its margins are not so clearly 

 outlined. It is of considerable thickness throughout, and is the 

 lateral boundary of a semi-crescentic area — well seen in E. 

 Fischer's ('03) illustration of the skull of macacus cynomolgus, 

 and also in Voit's picture of the skull of lepus — which may be 

 known as the paraforaminal area (fig. 2) . It is bounded medially 

 by the rounded edge of the neural arch, and ventrally by the 

 caudal border of the paracondyloid process. Its hollowed cen- 

 tral portion, which represents the lower surface of the lamina 

 alaris, has been before referred to, and on the right side has been 

 seen to be perforated by the minute condylar foramen. We 

 find, therefore, that the thickest parts of the squama are situated 

 immediately behind and below the ear capsule, and are represented 

 by the lateral occipital eminence and the crescentic ridge, the 

 former, just behind the capsulooccipital fissura, being slightly the 

 thicker. The area dorsal to a line passing from the dorsal forami- 

 nal prominence to the occipitoparietal fissure is very thin, and pre- 

 sents a short distance behind this line evidence of commencing ossi- 

 fication. The cartilage appears to be undergoing greatest change 

 in the region immediately dorso-lateral to the tip of the superior 



