I.—Notes on new or imperfectly known Chalk Polyzoa

Abstract

One of D'Orbigny's subsidiary methods of classification was to create separate genera for those species which heap layer upon layer of zoœcia by prefixing ‘Mult’ or ‘Multi’ to the name of the genus to which they would but for this habit of growth be referred. It is rather surprising that he did not have occasion to create a genus Multeschara, as there are two species in the English Chalk which he could only have dealt with in this way. They are of interest in their bearing on the question of the admissibility of methods of growth in classifying the Cheilostomata, as they are linked together by a most adventitious peculiarity in growth and one which does not involve any zoœcial modification. They offer therefore a case in which, if those who will not allow to zoarial growth and measure of classificatory value are right, it might be anticipated that species so linked together would be a heterogeneous assembly and not even consistent in this habit of growth. Such an anticipation would hardly be borne out in the case of the English Chalk. The Multescharine habit is practically confined to the two following species, which are most distinctly homogeneous, and neither of which, as far as my experience goes, ever adopts any other mode of growth (except for occasional specimens of Rhagasostoma palpigerum of purely Escharine habit, which may fairly be regarded as cut off prematurely in the Escharine stage, through which every ‘Multeschara’ must pass).