302 H. W. NORRIS 
minute twigs supply chiefly the walls of blood vessels in the dorso- 
lateral pharyngeal wall. The posterior palatine (pc.) contains 
some deeply medullated fibers. Most of these pass into a branch 
which terminates in a small vestigial muscle (figs. 13, 38, sh.) 
which has its origin on the fascia between the quadrate and the 
lateral edge of the parasphenoid and its insertion on the lateral 
border of the ceratohyal cartilage. That motor fibers should 
occur in a branch of the palatine and alveolar rami seems so 
improbable that the writer ventures little more than a bare state- 
ment of fact. Wilder says (’91, p. 663) that a few of the anterior 
fibers of the cerato-hyoideus externus muscle are innervated by 
the posterior palatine nerve, but this vestigial muscle is certainly 
no part of the ceratohyoideus externus muscle. The vestigial 
muscle is uniformly present, but, like most rudimentary struc- 
tures, varies greatly in the degree of its development. With the 
giving off of the branch to the muscle the posterior palatine be- 
comes much attenuated and passes posteriorly (jc.) into the ramus 
pretrematicus IX, uniting with it in two anastomoses, one with 
the main pretrematic trunk, the other with a small branch which 
arises far posteriorly near where the pretrematic leaves the glosso- 
pharyngeal ganglion. Whatever may be the significance of the 
branch terminating in the rudimentary muscle it is seen that the 
posterior palatine in Siren is in part a Jacobson’s anastomosis, for, 
while the latter typically unites with the palatinus, in Siren it 
joins the common trunk from which the palatine and alveolar 
rami arise. 
A search through the literature on the subject reveals no men- 
tion of a muscle in the other Urodela similar to this rudimen- 
tary one in Siren. Schulze (’92, p. 21) describes in the larva of 
the anurous Pelobates fuscus a muscle, m. suspensorio-hyoideus, 
which has its origin ‘‘von der lateralen Randparthie der Unter- 
seite des Corpus suspensorii und des dicht hinter dem Corpus 
suspensorii folgenden Theiles des Suspensoriums,’’ and is in- 
serted 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 hyoman- 
dibularis VII. 
