Structure of the caecilian Siphonops annulatus (Amphibia, Gymnophiona): general aspect of the body, disposition of the organs and structure of the mouth, oesophagus and stomach

The caecilians (or Gymnophiona) constitute one of the least well known grou ps of terrestrial vertebrates because most species live underground, in qui te unaccessible environments. Siphanops annulatus is an exclusively fossori al species and is the most extensively distributed caecilian in South Ameri ca. This work is the first of a series which intends to study the complete morphology of this species. It describes the general anatomy and the initia l portion of the digestive system, from the mouth to the stomach. The gener al aspect of the body and the elongation of the organs seem to be related t o adaptation to the fossorial environment.