THE YPSILOID APPARATUS OF URODELES. 273 



pulnca, resp. deren Verlangerung zur Symphysenbildung abge- 

 gliedertes Gebilde sein kann, da dasselbe sich als einheitlicher 

 Knorpel vor dem proximalen Ende der Symphyse anlegt, gleich- 

 falls nicht zugestimmt werden." 



Baur, basing his reason upon the fact of the completely paired 

 origin of the true epigastroid (/. e., epipubic) process, as shown 

 by Ncctnnts, for example, draws the following very definite con- 

 clusion with regard to this unpaired, more anterior structure, the 

 Cartilago ypsiloidcs : 



" I believe the ypsiloid cartilages are of secondary origin, de- 

 veloping independently from the gastroid (i. c., pubic) cartilage. 

 The long epigastroid of the Chclyiidce is homologue to the 

 short epigastroid in Testudinidce ; homologue to the anterior 

 portion of the gastroid cartilage in Ncctrtnts ; homologue to that 

 portion of the gastroid in salamanders and Dactylctra to which 

 the ypsiloid cartilages are connected. I consider these cartilages 

 as a later acquisition and they may develop in any group, Batra- 

 chia, Pterosaur ia, Monotreniata, Marsiipnlia" So far, even, as 

 similarity in location between the Cartilago ypsiloides and the 

 epipubic process of the lower Urodeles is concerned, I have been 

 unable to find any ground for the homology. In none of the 

 Urodeles in which the Cartilago ypsiloidcs is lacking have I found 

 the epipubic process crossing even a single myotome of the 

 rectus abdominis. In Necturus, the form in which the epipubic 

 process is most conspicuously developed, there is merely a cor- 

 responding narrowing of the posterior myotomes of the rectus 

 abdominis, particularly the first one (Fig. 8). 



Whether the ypsiloid cartilage is ever in any case continuous 

 with the pubis or not, it is very evidently a separate structure, 

 an independent chondrification of the linea alba of much later 

 origin than the pelvic girdle to which it sooner or later becomes 

 articulated. Thus considered, the ypsiloid cartilage presents no 

 obstacle to the idea of the paired nature of the anlage of the 

 pelvic girdle. Its existence is moreover explained quite in ac- 

 cordance with the principle which accounts for the origin of 

 similar structures (e. g., the sternebrae of Nccturus] in those con- 

 nective tissue regions where especially strong origin or insertion 

 of the muscle fibers is necessary. I have not had the opportunity 



