800 
THE VOYAGE OF H.M.S. CHALLENGER. 
ties in their anatomy or thrown any important light on their classification. Results 
seem to show that ancestral forms such as the Helioporidae are to he sought rather in 
shallow water than in the abyssal zones. There are no representatives of the most 
characteristic of the Palaeozoic Corals such as Zaphrentis, Cystiphyllum, Stauria, or 
Goniophyllum in the deep sea. Possible representatives of the Cyathonaxidae have 
indeed been obtained in Guynia, described by Professor Martin Duncan, and Haplo- 
pliyllia and Duncania, described by the late Count Pourtales, but the Cyathonaxidae 
are the least aberrant and characteristic members of the so-called Rugosa. Pourtales 
justly felt doubtful whether the arrangement of the septa in four systems instead of 
six could in itself be considered as a criterion of the Rugosa, and in the cases of 
Haplophyllia and Duncania the septa may be described rather as devoid of any 
definite numerical arrangement than as exhibiting any tetrameral symmetry. Further, 
Mr. Moseley has lately examined, by means of sections, the structure of the soft parts 
of Duncania in a specimen provided by Mr. A. Agassiz for the purpose, and finds that 
with regard to the peculiar arrangement of the longitudinal septal muscles and the 
demarcation of the directive septa, the coral agrees essentially with the Hexaetiniaria 
such as Caryophyllia, and all other modern Madreporaria, the anatomy of which has 
been adequately investigated.” 
