. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. Figure 20. Left stapes-quadrate of Eocaecilia micropodia, MCZ 9169. (A) dorsal, (B) ventral, (C) anterior, (D) lateral, (E) medial, (F) posterior views. therefore, the bar appears not to be a com- ponent of the jaw joint. In most gymnophionans the quadrate and stapes retain separate identities. The apparent fusion of the stapes-quadrate in Eocaecilia micropodia represents a more derived condition than that of some Re- cent caecilians in which the quadrate and stapes are closely abutted and even artic- ulate b
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. Figure 20. Left stapes-quadrate of Eocaecilia micropodia, MCZ 9169. (A) dorsal, (B) ventral, (C) anterior, (D) lateral, (E) medial, (F) posterior views. therefore, the bar appears not to be a com- ponent of the jaw joint. In most gymnophionans the quadrate and stapes retain separate identities. The apparent fusion of the stapes-quadrate in Eocaecilia micropodia represents a more derived condition than that of some Re- cent caecilians in which the quadrate and stapes are closely abutted and even artic- ulate by means of a synovial joint. In a ju- venile Ichthyophis glutinosus, for example, de Jager (1939b) described a synovial joint between the stapes and quadrate. Serial sections of adult Ichthyophis glutinosus (Fig. 23) and a specimen of Epicrionops petersi examined by confirm an ex- tensive contact between the quadrate and stapes. Yet E. micropodia is not unique among known caecilians for having com- pletely departed from the ancestral con- dition of a distinct stapes and quadrate. Scolecomorphids lack stapes as well as fo- ramina ovales (Nussbaum, 1985). Speci- mens of Boulengerula boulengeri were re- ported by de Villiers (1936, 1938) to vari- ably exhibit a synovial articulation between the stapes and quadrate or partial fusion of the two bones, do Jager (J 939a) de- scribed an incipient fusion of the stapes and quadrate in Dermophis niexicanus, but this condition was not confirmed by Wake and Ilanken (1982: 214), who reported that "the stapes is always free of the quad- rate. . ." In D. mexicanus, however, the quadrate fuses with the pterygoid (Wake and Ilanken, 1982;, a condition that Law- son (1963) believed to be present in Hy- pogeophis rostratus. The massive stapes-quadrate, intimately articulated with the quadrate ramus of the pterygoid and functioning in the jaw artic- ulation, presumably could have transmit- ted vibrations by bone conductance. Sta- pe
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