CHONDROCRANIUM OF EUMECES 161 
procartilage structure passing from one to the other without 
interruption or histological modification. In stage 2 the carti- 
lages are still so close together that the surrounding condensed 
connective tissue is confluent. In the later stages the separation 
becomes gradually greater, and no connective-tissue band re- 
mains to suggest the earlier union. This connection was noted 
in Lacerta by Hoffmann (’89), and is confirmed by Gaupp (’00, 
05 b), Fuchs (07 a), and Cords (09). In Sphenodon, according 
to Versluys (98, ’03), Schauinsland (’00), Howes and Swinnerton 
(01), and Fuchs (09), the union is permanent, although some 
peculiarities justify a question whether, in this case, it is primitive 
or secondary. As an embryonic structure it has also been de- 
seribed in Tropidonotus by Rathke (39, cited by Versluys, ’98) 
and Parker (’78), in Crocodilus by Parker (’83), and in Testudo 
by Bender (11). The connection is traced by Kingsley (00) 
to the stapes rather than the extracolumella—due apparently 
to a different identification of the junction of the two parts of 
the columella in the undifferentiated cartilaginous tissue of the 
embryo. It is significant that the connection of the columella 
and hyoid arch is recorded for each of the five main divisions of 
living reptiles; the frequent negative reports are not to be won- 
dered at, as the connection is usually very transitory. Dis- 
cussion of its significance is deferred to a later paragraph (p. 162). 
The relations of the ramus hyomandibularis of the facial nerve 
(fig. 16, n.VII.hy.) and its branch, the chorda tympani (figs. 
16, 17, and 18, n.VII.c.t.), to the skeletal parts may be sum- 
marized very briefly, as they are identical with those in Lacerta. 
The ramus hyomandibularis passes backward over the stalk of 
the columella auris (fig. 16), and gives off the chorda tympani. 
The latter extends forward, almost parallel to the hyomandibular 
ramus, passing above the ‘tendon of the extracolumella,’ already 
described, and the stalk of the columella (fig. 16). It then 
follows the ventral edge of the quadrate (figs. 17 and 18) for 
some distance, finally leaving it and bending sharply downward 
to reach the processus retroarticularis of Meckel’s cartilage. 
It is with hesitation that I touch upon the question of the 
origin and nature of the columella auris. Among recent writers, 
