Some aberrant foraminifera from the shelf sediments of central east coast of India

Abstract

A rich foraminiferal outer shelf assemblage has yielded some aberrant forms in the case of @iUvigerina@@ sp. @iSiphonoperta@@ sp., and @iNodosaria@@ sp. The aberration is (1) in the development of two terminal apertures with parallel necks and phialineiips in @iUvigerina@@ sp., (2) a twinned case in another @iUvigerina@@ sp., (3) development of two end chambers as last chamber instead of the usual one only in the case of @iSiphonoperta@@ sp., and (4) @iNodosaria@@ sp., showing a 'bend' at an angle after being straight for sometime. It is concluded that, after considering several causes for the aberrations, the two apertural @iUvigerina@@ sp., and the finally terminated two chambered @iSiphonoperta@@ sp., are cases of phylogerontism showing over-specialisation; the twinning in @iUvigerina@@ sp., as due to an accidental coalescence of two tests in the early stages of growth, and @iNodosaria@@ sp., showing a 'bend' as a result of damaged last chamber being recalcified with the terminal aperture shifting to an angle and continue to grow further maintaining the same direction. Thus, it appears to be a clear case of regeneration