The Intestine in Members of the Genus Rajaand Host-specificity in the Tetraphyllidea

Abstract

IT was recently found that some species of the genus Raja could be distinguished solely on differences in the morphology of their spiral valves, in particular, from the form of their mucosæ. A brief account of the latter is given here because, so far as I know, these differences have not been described previously. In addition, it is thought that variations of this kind may explain, in part, the high degree of host specificity found in the Tetraphyllidea, and may have a bearing on specificity in other orders of the Cestoda. A more detailed account of the work will be published elsewhere.