96 Dr. J. E. Duerden on the 



called lahyrintMca, then the name must be rvjoar/a, because it 

 occurs earlier on the page than lahyrinthica. 



If this conclusion be contrary to the International Rules, 

 they must bo very strange rules. 



As to whether, when the type has been lost, the two names 

 are to be regarded as denoting the same species or not, is 

 entirely a matter for mutual discussion between arachnolo- 

 gists, who, if possible, would come to some definite conclusion 

 on the point. 



XIV. — The Morphology of thu Madreporaria. — II. Increase 

 of Mesenteries in Madrepora hey and the Protocnemic Stng-e, 

 By J. E. Duerden, Ph.D., A.R.C.Sc. (Lend.), Bruce 

 Fellow, Johns Hopkins University *. 



In tlie 'Johns Hopkins University Circulars^ (1900)^ I refer 

 briefly to the discovery that in the genus Porites the mesen- 

 teries beyond the primary six pairs (protocnemes) are- added 

 in bilateral pairs, within the entocoele of either the dorsal or 

 ventral pair of directives. This method of mesenterial increase 

 is shown to differ from that characteristic of recent corals 

 generally. The results are also briefly contrasted with the 

 method of mesenterial increase occurring in the three great 

 divisions of the Actiniaria — Hexactinige, Zoanthese, and 

 Cerianthea?. The close resemblance of the polyps of Madre- 

 pora t to those of Porites, with regard to tlie number and 

 arrangement of the tentacles and mesenteries, suggested that 

 perhaps a similar mode of mesenterial addition might be 

 followed in that genus also, and tlie present investigation was 

 undertaken to determine thi.^. 



In West-Indian waters at least three well-known types of 



* From tlie ' Johns Hopkins University Circulars/ vol. xxi. No. 157, 

 pp. 59-66 (April, 1902). For Part I. see ' Annals ' for May 1902, p. 381. 



t Since the paper was written 1 have received Mr.' T. Wayland 

 Vaughan's reports, " Some Fossil Corals from the Elevated Reefs of 

 CuraQao, Arube, and Bonaire," and " The Stony Corals of the Porto 

 Bican Waters," 1901. Following Brook (1893), Vaughan points out that 

 none of the species at present called Madrepora were included witliin 

 this genus by Linnfeus in 1758, and that therefore the name cannot be 

 retained for the forms embraced by Dana, Milne-Edwards and Ilaime, 

 and later authors. Vaughan suggests its replacement by Isopora, a term 

 first employed by Studer in 1878 in a subgeneric sense. More recently 

 Prof. A. E. Verrill (1901) has come to the conclusion that the Acvopora 

 of Oken (1815) has much better claims for adoption in pLace of Mtnlre- 

 pora. 



