CHONDROCRANIUM OF EUMECES 199 
of dorsal and ventral divisions. The ventral, throughout the 
vertebrate series, consists of Meckel’s cartilage, the cartilage of 
the lower jaw; the dorsal consists of a more or less continuous 
bar of cartilage, the’ palato-pterygo-quadrate cartilage, furnishing 
the primitive supporting apparatus or suspensorium for the 
lower jaw. 
In early stages of Sphenodon (Howes and Swinnerton, ’01), 
Lacerta (Cords, 09), Testudo (Bender, 712), and Crocodilus 
(Shiino, 714) the dorsal and ventral divisions of this arch are 
described as represented by a single continuous mass of blastema. 
This condition is probably general, but the articulation is already 
well developed in the earliest observed stages of Eumeces. 
2. Dorsal division—palato-pterygo-quadrate cartilage 
In the Anura (Gaupp, 793; Fuchs, ’09) there is a continuous 
bar of cartilage extending from the nasal capsule to the otic 
capsule; in the reptiles this has suffered a varying degree of 
degeneration. In Eumeces only the posterior portion is highly 
developed. This appears as a large and well-formed quadrate 
cartilage (fig. 3, quad.), extending forward and somewhat down- 
ward from the neighborhood of the crista parotica of the otic 
capsule to the articulation of the lower jaw. Its general form is 
that of a thick and rather narrow plate, so twisted in its course 
that its upper end approaches a parasagittal plane (fig. 11), 
while its lower articular extremity is more nearly horizontal 
(fig. 17). The articular surface is saddle-shaped—convex in 
parasagittal, concave in horizontal section. The lateral portion 
of the articular surface is extended as a conspicuous process, 
giving an oblique form to this end of the cartilage (fig. 2). In 
its middle third the dorsal edge of the quadrate is raised into a 
fine projecting crest with slightly thickened and outwardly rolled 
margin (figs. 3, 10, 12, and 16). In stage 6 this projecting edge 
is much more strikingly recurved, so that it comes to form an 
almost semicircular frame for the support of the dorsal side of 
the developing tympanic membrane. 
In Lacerta this crest is much less developed than in Eumeces; 
in Emys (Kunkel, 712 b) and Testudo (Bender, ’12) it is enor- 
JOURNAL OF MORPHOLOGY, VOL. 34, No. 1 
