• 1
     Stages in the developmental differentiation of the stomach are described in a graded series of embryos and foetuses of Semnopithecus priam with special reference to morphogenetic and histogenetic features.
  • 2
     Comparison is made with material from Colobus (Piliocolobus) badius and with data from the literature regarding some other Asiatic colobid monkeys.
  • 3
     Neonatal stages are considered in Semnopithecus, Kasi, Trachypithecus and Presbytis, with special reference to the morphological changes involving the liver.
  • 4
     Conclusions are (a) that although the colobid stomach presents features of a primitive order, in so far as these recall embryonic conditions, the viscus, both as a whole and in its details, is secondarily specialized in adaptation to a specialized diet. This simply means that embryonal gastric characters have been utilized in the elaboration of the definitive organ, whereas in the other Old World pithecoids the stomach has undergone a divergent simplification; (b) some evidence is indicated of intergeneric differentiation in gastric morphology whithin the family, e.g. in Procolobus and Nasalis especially; (c) the mutual topographical relations of stomach and liver as observed in adult colobids are post-natal and result from several independent factors, especially (i) prenatal hepatic function and (ii) post-natal gastric function.