Notes accompanying two slides of Carboniferous Polyzoa from shales at Hairmyres, near East Kilbride, Lanarkshire

Abstract

1. Rhabdomeson gracile, Phillip’s species, genus nov. In the ‶Annals and Magazine of Natural History″ for May 1874, Dr Young and I have founded a new genus upon the internal structure of the organism formerly known as Ceriopora ( Millepora gracilis ) of Phillips, and in order to make sure of the identity of the species upon which our remarks are founded, we submitted specimens of the organism to the late Prof. Phillips for examination shortly before his death, which he in a letter stated to be identical with the species which he first described in the ‶Palaeozoic Fossils of Devon″ as M. gracilis. In our paper in the ‶Annals″ we have pointed out that a coral and a polyzoon have been confused together; and, further, that the various palaeontologists who have subsequently remarked on Phillip’s species have only noticed or described the external characters of the organism, but have failed to observe the peculiar and important character of its central rod or axis, around which the cells are arranged in quincuncial order, and upon which feature the genus Rhabdomeson has been established by us. Except in Professor Allman’s recent genus Rhabdopleura, no other polyzoon, recent nor fossil, is known to have an axis upon which the cells are placed. In Rhabdopleura the axis is lateral, in Rhabdomeson it is central. We have since ascertained that Ceriopora ( M. rhombifera ), Phillips, which is a much rarer and more slender species than M. gracilis, but having the same habit of growth, also possesses a