484 DE. W. G. EIDEWOOD ON THE LAEVAL HYOEEANCHIAL 



dytes is correspondingly long in an antero-posterior direction 

 while the outline of this fibrous mass is nearly square in Pelohates 

 and Leptohrachium. 



The lateral parts of the ceratohyals are exceptionally massive 

 in Leptohrachiu7n, and this genus is also remarkable in having 

 the incipient laryngeal sinus bounded laterally, not by the hypo- 

 branchial cartilage tipped with the spiculum of the fourth 

 branchial arch, but by the spicula alone (fig. 4, Is.'). These 

 latter are so largely developed as to simulate early and auto- 

 genous thyrohyals. In fact their exceptional proportions in this 

 early stage may actually affect the later development of the 

 thyrohyals. I have been unable to procure older larvae of 

 Leptohrachmm to determine this point. 



DlSCOGIiOSSID^. 



As already mentioned in the earlier part of this paper, there 

 is a remarkable similarity in the structure of the larval hyo- 

 branchial apparatus in the three genera Alytes, Bomhinator, and 

 Discoglossus. The characters which they have in common, and 

 which do not occur in any other Anuran larva examined, are : — 

 the presence of an anterior copula in front of the pars reuniens, 

 and the complete separation of the two hypobrauchial plates by 

 the large posterior copula situated behind the pars reuniens. 

 I have already stated, in a paper presented to the Zoological 

 Society in November 1897, that the credit of the discovery of the 

 anterior copula of Alytes belongs to Graupp (4. pp. 411-412). 

 The figure which Gotte has given of the larval hyobranehial 

 skeleton of JBomhinator (5. Taf. xviii. fig. 332) shows very well 

 the extremely small size of the cleft between the third and fourth 

 ceratobranchials, but the axial parts of the skeleton are rather 

 indistinct. Three areas, probably representing the anterior and 

 posterior copulas with the fibrous pars reuniens between, can be 

 distinguished, but no special notice is taken of the relations or 

 the morphology of the parts. The earlier figures of Bomhinator 

 by Eeichert (10. Taf. i. figs. 20 and 23) are so imperfect as to 

 call for no detailed criticism. 



In all three genera the transverse diameter of the anterior 

 copula is greater than the longitudinal, and the copula is sepa- 

 rated from the pars reuniens by a small space — quite minute in 

 Discoglossus. The space between the antero-lateral border of 



