86 APODA CHAP. 



orbito-ethmoidal region of the primordial skull is also turned 

 into one mass of bone. 



The angular element of the lower jaw forms a thick and 

 large process which projects upwards and backwards from the 

 mandibular joint. The former possession of a splenial bone 

 is indicated by the occurrence of a second series of teeth in 

 the mandibles of IclithyopMs and Uraeotyplilvs. Other genera 

 have vestiges of this second row, or it may be completely 

 lost. 



The hyoid and branchial apparatus is more primitive than 

 in any other recent Amphibia. In the larva the hyoid and the 

 first and second branchial arches are connected with each other 

 by a median copular piece. The third branchial arches are free 

 from the rest, but are fused in the middle line, the fourth are 

 loosely attached to the previous pair. In the adult both fuse 

 into one transverse, curved bar, and the second pair of brauchials 

 lose their connexion with the basal longitudinal piece and likewise 

 form a transverse bar. 



The vertebrae are built upon the pseudocentrous type, are 

 amphicoelous, and the chorda is intravertebrally destroyed by 

 cartilage, as in the majority of the Urodela. The number of 

 vertebrae is great, amounting in some species to between 200 

 and 300, of which a few belong to the tail. The first vertebra 

 is devoid of an odontoid process. The ribs are proximally 

 bifurcated as in the Urodela. 



The eyes are practically useless, being either more or 

 less concealed under the skin, or they are covered by the 

 maxillary bones. All Coecilians possess a peculiar tentacular 

 sensory apparatus, which consists of a conical tiap-shaped or 

 globular soft tentacle, which is lodged in a .special groove or 

 canal of tlie maxilla, between the eye and the nose, whence it is 

 frequently protruded while the animal is crawling about. These 

 tentacles in the young Si2:)honops lie, according to the Sarasins, 

 quite close to the eyes, but are later transferred nearer to the 

 nose. The organ consists of a peculiarly rolled up and pointed 

 fold which arises from the bottom of the sac or pit, where it 

 receives a nerve. It is protruded by becoming turgid with 

 l)lood, and is retracted by a strong muscle. Into the lumen of 

 the sac are poured secretions from the large orbital (Harderian) 

 gland, to keep the apparatus clean. Hence arose the mistaken 



