210 EDWARD L. RICE 
30. Solum nasi, in strict sense, greatly reduced; originally 
free, and first united with lateral wall in stage 6, forming nearest 
equivalent of zona annularis of Lacerta—incomplete even in 
this stage owing to dorsal interruption of enormous fenestra 
superior nasi | 
31. Posterior edge of rudimentary solum nasi divided into 
three lobes—lateral, cartilago ectochoanalis; intermediate, thick- 
ened to form concha of Jacobson’s organ; median, continuous, 
in stage 6, with paraseptal cartilage. Paraseptal cartilage con- 
tinuous posteriorly with planum antorbitale; but planum antor- 
bitale and paraseptal cartilage free, in all stages, from septum. 
32. Fenestra olfactoria and fissura orbitonasalis separated by 
sphenethmoid cartilage. 
33. Continuous palato-pterygo-quadrate ramus of amphibian 
mandibular arch represented in stage 5 of Eumeces by the fol- 
lowing distinct elements: maxillary processes, including palatine 
extension of posterior process; processus pterygoideus, including 
occasional isolated anterior fragment; epipterygoid (= processus 
ascendens of quadrate); quadrate; probably, also, articular 
cartilage of pterygoid. Processus pterygoideus and epipterygoid 
continuous with quadrate in earlier stages; apparently also con- 
tinuous, through articular cartilage, with processus basiptery- 
goideus. 
34. Meckel’s cartilage ‘very slender, and processus retro- 
articularis conspicuously developed. No independent ‘basiman- 
dibular’ element in symphysis. 
35. Body of hyoid extended into long and slender processus 
lingualis; hyoid arch and first and second branchial arches well 
developed. Pair of unattached cartilages tentatively inter- 
preted as isolated fragments of second branchial arches. 
36. Development of hyobranchial apparatus marked by 
progressive division of originally continuous mass into somewhat 
distinct elements; correlated with this the early separation of 
hyoid arch and columella auris. 
