in SKULL 43 



towards the nostril. Next follows the maxilla (MX), a long, curved 

 bone, forming the greater part of the upper jaw, and joined at its 

 posterior end to a small, slender bone, the quadrato-jugal (QU.JU), 

 which is firmly connected with the lower end of the suspensorium. 

 Both premaxilla and maxilla are produced below into a prominent edge 

 from which spring a number of small conical teeth, arranged in a 

 single row. 



Besides these three bones there are two others which seem, as it were, 

 to brace the upper jaw to the brain-case and suspensorium. The 

 palatine (PAL) is a narrow, rod-like bone, placed transversely behind 

 the olfactory capsule. The pterygoid (PTG) is a large, three-rayed 

 bone ; one ray is directed forward and connected with the outer end of 

 the palatine and with the inner face of the maxilla; another passes 

 backwards and inwards and is connected with the auditory capsule ; the 

 third extends backwards and outwards and forms the inner and ventral 

 portion of the suspensorium. The main mass or core of the suspen- 

 sorium, between the squamosal outside and the pterygoid v/ithin, is a 

 rod of cartilage (stts), which is continued forwards by a bar (pal. qu] 

 supporting the pterygoid and palatine. 



There is an important distinction to be drawn between the bones of 

 the 'skull which can be made out only by the exercise of a good deal of 

 care and patience. By softening the connective -tissue which binds the 

 bones together, it is possible to remove the majority of them without 

 injuring the underlying cartilage (compare the right and left sides of the 

 skull in Figs. 8 and 9, A and C), provided, of course, that the opera- 

 tion is skilfully performed : these bones are the nasals, vomers, fronto- 

 parietals, parasphenoid, premaxillae, maxillae, quadrato-jugals, palatines, 

 pterygoids, and squamosals. A sort of foundation or groundwork (left 

 side of figure in Figs. 8 and 9, A ; right side in Fig. 9, C) is then left 

 behind, consisting mainly of cartilage, but containing the exoccipitals, 

 pro-otics, and girdle-bone. These five bones cannot be removed 

 without pulling the cartilaginous groundwork or chondro cranium to 

 pieces. We thus get a distinction between replacing bones (" cartilage- 

 bones ") which are actually continuous with the cartilage and form part 

 of the chondrocranium and investing bones (" membrane bones") which 

 lie outside the chondrocranium, united to it only by connective tissue. 



The chondrocranium has a cartilaginous roof, underlying the fronto- 

 parietals ; it is pierced by one large (Fig. S,fon) and two small (fort') 

 spaces, oa&z&fontanelles, covered by membrane. It has also a cartila- 



