518 



homolog}^ with the muscles in Amphiuma termed retractor and levator 

 bulbi. They evidently do not correspond to any of the muscles described 

 by Bruner (1901) in the Urodela and Anura, Avhich are concerned 

 with the regulation of the size of the opening of the prenaris. 



Wilder states that in Siren a '^ ramus palatinus posterior" of the 

 facial nerve innervates a few of the anterior fibers of the cerato- 

 hyoideus externus muscle. Such an arrangement seems anomalous 

 and calls for a critical examination of the evidence. The writer finds 

 that from the common trunk of the rami palatinus et alveolaris facialis 

 there is given off posteriorly a small nerve, the ramus palatinus 

 posterior of Wilder, which contains among its non-medullated fibers 

 some deeply medullated ones. Most of the latter pass into a branch 

 that terminates in a small vestigial muscle which has its origin on 

 the fascia between the quadrate cartilage and the lateral edge of the 

 parasphenoid bone and its insertion on the lateral border of the 

 ceratohyal cartilage. That motor fibers should occur in a branch of 

 the alveolar and palatine rami seems so improbable that the writer 

 ventures little more than the mere statement of the fact. The muscle 

 concerned is certainly not a part of the cerato-hyoideus externus 

 muscle. It is, however, without exception present in all the specimens 

 examined, but like most vestigial structures varies greatly in the 

 degree of its development. In the larval stage, of which the writer 

 has no material, it is doubtless of some functional importance. 

 A search through the literature on this subject reveals no mention 

 of a muscle in the urodela similar to this rudimentary one in Siren. 

 ScHULTZE (1892) describes in the larva of the anuran Pelobates fuscus 

 a muscle, m. suspensorio-hyoideus, that has its origin '" von der lateralen 

 Randparthie des Corpus suspensorii und des dicht hinter dem Corpus 

 suspensorii folgenden Theiles des Suspensoriums", and is inserted on 

 the "processus lateralis" of the ceratohyal. In the larval condition 

 of Rana pipiens and R. catesbiana the writer finds a similar muscle 

 innervated by a branch of the truncus hyomandibularis facialis. 



Literature Cited. 



Bruner, H. L. 1901. The smooth facial muscles of Anura and Salamandrina, 

 a contribution to the anatomy and physiology of the respiratory mech- 

 anism of the amphibians. Morph. Jahrb., Bd. 29. 



Fischer, J. G. 1864. Anatomische Abhandlungen über die Perennibranchiaten 

 und Derotremen. Hamburs-. 



