48 THE ANATOMY OF HYLA C.ERULEA WHITE. 



forms is transverse and not vertical or parallel to the long 

 axis of the animal. The omosternum is situated anteriorly 

 to the epieoracoids, and unites the two pectoral components 

 in this region. On tearing the girdle components apart, 

 the omosternum divides into two — each part remaining 

 attached to its corresponding epicoracoid. There is a 

 constriction between the omosternum and the epieoracoids. 

 The xiphisternum (Fig. 1, xip. st.) is a flattened 

 cartilaginous plate with two posteriorly directed cornua. 

 We find that they are not so slender as figured by Parker 

 for Calamites cyanea, neither are they so stout as those 

 of his Acrodytes daudinii, the form Beddard (1) says Hyla 

 caendea exactly resembles in regard to the sternum. The 

 condition observed by us is intermediate between the two. 

 In our specimens the outer border is convex, while in 

 Calamites cyanea it is straight. Each cornu is thickened 

 in the mid-longitudinal line. Arising on each side of the 

 ventral mid-line of the anterior undivided portion of the 

 xiphisternum is a transverse ridge (Fig. 1, r.) running a 

 little posteriorly. These two ridges are ventral to the 

 epieoracoids and overlap their posterior edges. Anteriorly, 

 an oblique median septum separates the two compartments 

 formed by the transverse ridges. The xiphisternum is 

 connected to the pectoral arch by connective tissue. The 

 sterno-hyoid muscle arises as tAvo strands from the dorsal 

 surfaces of the xiphisternal cornua — a strand from each 

 cornu. The fibres pass anteriorly, and are inserted into 

 the body of the hyoid. 



Vertebral Column. 

 The vertebral column (Fig. 3) consists of the typical 

 Anuran components, viz. : — nine vertebrse including the 

 atlas, and a urostyle or os coccygeum. Hyla ccerulea 

 agrees with the Other species of Hylidce in having the 

 sacral transverse processes or diapophyses expanded. 

 The transverse processes of the vertebrse fall into two 

 groups in regard to size. Those of the second, third, 

 fourth and ninth are well developed, while those of the 

 fifth, sixth, seventh and eighth are comparatively slender. 

 Tn the second-eighth vertebrse the posterior notches in the 

 pedicles, forming the anterior portions of the inter-vertebral 

 foramina, are larger than the anterior ones. The anterior 



