584 AMPHIBIA. 
pensorium ; in Teleosteans the name is applied to the hyomandibular 
and symplectic ; in Sauropsida the quadrate occasionally gets the same 
confusing title. 
When the lower jaw is connected with the skull wholly by elements 
of the hyoid arch, as in most Elasmobranchs and Ganoids, and all 
Teleosteans, the term hyostylic is used. When the connection is due 
to a quadrate element only, as in Amphibia and Sauropsida, it is 
called autostylic. When there is both a hyoid and a quadrate element, 
as in Lepzdosteus among Ganoids, or a hyoid and a palato-quadrate, as 
in Cestracton among Elasmobranchs and perhaps also in Holocephali, 
the term amphistylic is used. Finally, it may be noted here that in 
Mammals the lower jaw articulates with the squamosal. 
The first or mandibular arch gives origin inferiorly to Meckel’s 
cartilage, which forms the basis and persistent core of the lower 
jaw, and superiorly to the palato-pterygo-quadrate cartilage which 
is represented in the adult by the minute quadrate bone, by the 
suspensorial cartilage, and by other cartilages which are invested 
by the pterygoid and palatine bones. 
The second or hyoid arch gives origin inferiorly to the hyoid plate ; 
superiorly, according to Parker, to the columella. 
Of the four posterior branchial arches, there are in the adult some 
persistent remnants, ¢.g. in the larynx. 
The limbs and girdles.—The shoulder-girdle consists of 
a dorsal portion—the scapula and the partially cartilagi- 
nous supra-scapula, and of: a ventral portion—the coracoid 
and the pre-coracoid. With the latter, according to most 
authorities, a thin clavicle is associated. The glenoid 
cavity, with which the humerus articulates, is formed by the 
junction of scapula and coracoid. 
Between the median ends of the coracoids lie two fused 
cartilaginous epicoracoids, behind which is a bony part of 
the sternum, prolonged posteriorly into a notched cartila- 
ginous xiphisternum. Anteriorly lies a bony portion called 
the omosternum, which is prolonged forwards into an epi- 
sternum cartilage. This sternum does not arise like that of 
higher Vertebrates, from a fusion of the ventral ends of ribs. 
Indeed, there are no ribs in the frog, unless they be minute 
rudiments at the ends of the transverse processes. 
The true frogs (Ranidz) have what is called a firmdsternal pectoral 
arch, in which precoracoid and coracoid nearly abut on the middle line, 
and are only narrowly separated by the epicoracoids. In toads, tree-frogs, 
etc., the arch is arcéferal, the precoracoid and coracoid being widely 
separated medianly, and connected by a large arched epicoracoid, over- 
lapping its fellow. 
The skeleton of the fore-limb consists of an upper arm 
