218 OUTLINES OF CHORDATE DEVELOPMENT 



On each side, the hyoid cartilage or ceratohyal, extends dor- 

 sally, connecting with the palato-quadrate just behind the jaw 

 articulation; ventrally it unites with its fellow (Fig. 83). The 

 first branchials also unite ventrally. The other branchial 

 cartilages do not reach the mid-ventral line, but the lower end 

 of each unites with that anterior to it; later they similarly 

 connect dorsally. In the ventral region of the pharynx a 

 median element, the copula (basibranchial) appears, between 



FIG. 84. A. Hyobranchial apparatus of R. fusca, toward the end of meta- 

 morphosis. The left side is shown in a more advanced stage than the right, in 

 that less cartilage is present. The original cartilage is indicated by fine stipples. 

 The coarse stipples indicate the cartilage added during the early part of meta- 

 morphosis. After Gaupp, from Ziegler. B. Hyobranchial apparatus of a 2 cm. 

 R. fusca, after metamorphosis. After Gaupp, from Ziegler. a, Alar process; 

 ac, anterior process of hyoid cornu; 6, body of hyobranchial cartilage; bb, basi- 

 branchial (first), or copula; ch, ceratohyal (hyoid cornu inB); ho, hypobranchial 

 plate; I, postero-lateral process of hyobranchial cartilage; m, manubrium; 

 2, remains of second ceratobranchial (postero-medial process of hyobranchial 

 cartilage). 



the hyoid and the first branchial, connecting with the ventral 

 ends of both these arches. The basihyoid cartilage is repre- 

 sented only by a small median copula in front of the hyoid cartil- 

 age. The lower ends of the first branchials become flattened 

 and expanded as the hypobranchial plate, with which the ventral 

 ends of the other three branchials then fuse. Only the lateral 

 or middle sections of the branchial cartilages, between the 



