The Progress of Ossification in the Skull of the Cricketfrog Pseudacris nigrita triseriata

Abstract

Eggs of the three-lined cricketfrog Pseudacris nigrita triseriata were collected and the resulting larvae reared through metamorphosis. A series of young frogs was preserved, representing stages from the emergence of forelimbs through a period of 3 succeeding weeks. These specimens, together with some adult forms, were cleared in KOH, stained with alizarin red S for the demonstration of any calcification or ossification, and embedded in a plastic for more convenient handling. The extent of ossification and/or calcifica-in the skull at the time of forelimb emergence was determined, and the progress of ossification and/or calcification was followed through the series. Since Pseudacris nigrita triseriata has a relatively short larval period one might expect the sequence of ossification of its skull to be more like that in Eleutherodactylus nubicola which has no larval period. But the sequence of ossification in the cricketfrog more closely resembles that in Rana than that in either Triton or Eleutherodactylus.