476 DB. "W. G. EIDEWOOD O'N THE LAEYAL HTOBEANCHIAL 



to three distinct families. Without entering into a discussion 

 of the question whether the larval stages of Anura represent 

 a true recapitulation of ancestral evolution, the similarity in the 

 structure of the larval hyobranchial skeleton in these genera can, 

 I thiuk, be safely taken to indicate close genetic relationship. 



The position of the anterior copula of the Discoglossidse is in 

 almost all the other forms examined occupied by loose connective 

 tissue, the middle or hinder part of vphich is firmer and has the 

 form of a transverse ligamentous band (fig. 2, I) connecting the 

 ceratohyals. Gaupp, in his description of Bana tadpoles (4. 

 p. 404), alludes to this band as being partially cartilaginous. 

 Although I have failed to recognize anything approaching the 

 structure of cartilage in the ligament, I fully concur with this 

 author in regarding it as the morphological equivalent of the 

 anterior copula of Alytes. I have not succeeded in finding the 

 band in either Pelodytes, Xenopus^ or Pipa. 



Considerable diversity of form is observable in the shape of 

 the second or posterior copula, and the proportion which it bears 

 to the surrounding parts. It is usually longer than broad, but is 

 broader than long in Chiroleptes (fig. 7, cp.) and Telmatobius. 

 It is large in Pelobates (fig. 8), Leptohracliium (fig. 4), and the 

 Discoglossidse (fig. 1), but small in Chiroleptes (fig. 7) and 

 Phyllohates. 



Except in the Discoglossidse, where the posterior copula 

 extends back to the laryngeal sinus, the spaces at the right and 

 left sides of the copula vary directly in size with the copula 

 itself, being largest in Pelohates (fig. 8, s) and practically absent 

 in Phyllohates. The hypobranchial plates are very variable in 

 shape, the variability depending chiefly on the obliquity of their 

 anterior edges and the length of their internal or mesial margins. 

 These relations are themselves dependent on the proportionate 

 size of the posterior copula. Thus, iu Chiroleptes (fig. 7), the 

 antero-lateral edges of the hypobranchial cartilages are very 

 oblique and the median symphysis long, the copula being small and 

 the lateral spaces small. The opposite extreme is exemplified 

 by Pelohates (fig. 8), in which the anterior margin of the hypo- 

 branchial plate is strictly transverse and the symphysis short, 

 these features being correlated with the large size of the copula 

 and of its lateral spaces. Jlyla, Bufo, and JRana (fig. 2) occupy 

 intermediate positions between these extremes. 



