Glass 2. Pisces. 



365 



articulated above witli the skull^ and thus serves as suspensorium 

 for the mandibular, which, therefore, possesses no direct connec- 

 tion with the skull. This connection of the upper portions of 

 the mandibular and hyoid arches is specially close in the Teleosteans 

 and bony G-anoids, forming a continuous whole, in which the cartilage 

 is, for the most part, replaced by bone; it is less evident in the 

 cartilaginous Ganoids, although here, also, the two portions are 

 closely connected (for the Dipnoi, see below) : the mandibular 

 cartilage, which is now, however, more or less replaced and covered by 

 bone, and the hyoid, which is likewise more or less ossified, are 

 attached at the same point. Of the five branchial arches 

 which are usually partly ossified, or covered by bony plates, the last 

 is very short in the bony Ganoids and Teleosteans, the lowest joint 

 alone being present. The last branchial bars, which usually carry 

 numerous teeth, are termed the inferior pharyngeal bones. 

 The uppermost joints of some of the other gill-bars are toothed in a 

 similar way, and aro called the superior pharyngeal bones. 



Fig. 302. SkuH of a Cod. h — 7i' skull, Jiy hyomandibular, hy' lower portion of the- 

 hyoid, io interoperonlum {see p. 374), I quadrate, m premaxilla, o (left) maxiUa, o (right) 

 operculum, p pterygoid, pr preoperoulum, s suborbitals, so suboperoulum, st branohi ostegal 

 rays, (p. 374), t basibranohials, u mandible. 



In the Teleostei, the tipper portion of the mandibular arch is 

 represented by the following bones : below and behind by the quadrate, with 

 articular surfaces for the mandible ; then by several bones, which are termed 

 pterygoids; and anteriorly, by the palatine. The lower portion of 

 the mandibular arch is a cartilage, the upper end of which is ossified and bears 

 articular facets, whilst the rest is a thhi cartUaginotis rod ("Meckel's 

 cartilage), surrounded by membrane bones, of which the most important 



