Sense-organ-like parietal pits found in Psammophiini (Serpentes, Colubridae)

In several psammophine snake species, small sense-organ-like pits have been discovered occurring on the top of the head. These pits show a heretofore non-described structure. In numbers of one to four per head, they are present in Dromophis lineatus, Malpolon monspessulanus, several Psammophis species and Rhamphiophis rubropunctatus, but not in all individuals which is unrelated to sex. The reason for their sporadic occurrence remains obscure. Their equally obscure function is discussed in relation to the presumed functions of already known upper-head 'pits' in snakes. A histological study is in preparation.