618 ' EDWARD PHELPS ALLIS, JR. 
structure. Krawetz concluded (10, p. 360) that the stylus of all 
of the Urodela was represented in the strand of connective tis- 
sue that extends, in Ceratodus, from the anterior wall of the au- 
ditory capsule to the processus basalis palatoquadrati, but this 
strand of tissue lies ventral to the entire nerve instead of dorsal 
to, or straddling it. 
In the Sauria the columella is said to lie (Gaupp ’99, p. 1105, 
Kingsley ’00, p. 218) between the chorda tympani (mandibularis 
internus) and the ramus hyomandibularis facialis, posterior to the 
former and anterior to the latter. The columella accordingly has 
the relations to these two nerves that the hyomandibula of Poly- 
pterus has. The extracolumella of these animals is said by Kings- 
ley to be a primarily independent element, which later fuses com- 
pletely with the stapes, and he is strongly melined to consider 
it ‘‘as the remains of a visceral arch which has almost completely 
disappeared from between the hyoid and the mandibular arches,”’ 
and the homologue, possibly, of the spiracular cartilage of the 
Plagiostomi (1. c., pp. 232-235). In a figure (1. ¢., fig. 2) said to 
be of an early stage of the lizard, the hyal cartilages are all 
shown, and the stapes as there shown is evidently, if it lies ventral 
to the vena petroso-lateralis as it does in the Urodela, an epi- 
pharyngohyal and not simply a pharyngohyal, for it is continu- 
ous ventrally with the ceratohyal. The extracolumella has 
strikingly the position of the symplectic of the Chondrostei, and 
it would seem as if it must be the homologue of that cartilage 
rather than of the spiracular cartilage of the Plagiostomi, as 
Kingsley suggests. The relations of the veins, arteries and 
nerves of the region would doubtless determine this. 
The dissections of the several fishes examined in this work ° 
have all been prepared by my assistants, Mr. Jujiro Nom- 
ura and Mr. John Henry, Mr. Nomura’s work being limited to 
Chlamy-doselachus. The preparation and examination of the 
microscopical sections has all been done by Mr. Henry. 
