CERIOPORIDjE. 121 



As remarked by Mr. Lonsdale, 1 " the genus Heteropora, established in 1834 by M. do 

 Blainville on three species of Prof. Goldfuss's Ceriopora, has not been described either by 

 its founder or by other authorities with sufficient fulness to enable an opinion to be 

 formed of its complete characters, or of the nature of the minor openings, one of the 

 assigned essential structures." Nor consequently could its true systematic position be 

 regarded as fully established. Though unnoticed among the rest of the Tubuliporidans by 

 M. Milne-Edwards in his excellent Memoirs on those Polyzoa, published in 1838, it would 

 seem that he had surmised its true relations when he edited the second edition of Lamarck 

 in 1830. It is there placed among the heterogeneous " Polypiers foramines," of Lamarck, 

 together with its natural allies Pustulopora, Chrysaora, Theonoa, and Terebellaria, whence 

 it may be concluded that its true affinities were at any rate beginning to be appreciated. 

 But to Mr. Lonsdale is undoubtedly due the merit of clearly indicating upon sufficient 

 grounds the real position of the genus, which has been tacitly accepted by all subsequent 

 writers. 



The essential character of the genus has been drawn from the existence on the surface 

 of the Polyzoarium of two kinds of pores, a larger and a smaller. The former representing 

 the orifices of the true polypicle-cells, and the latter those of interstitial canals or tubular 

 passages of greater or less length, and which are of smaller size though far more nume- 

 rous than the true cells, and in some instances differ from them not only in size, but also 

 in structure. The true nature of these interstitial passages is at present obscure ; and as 

 no living species belonging to the genus has, so far as I know, yet been met with, one 

 important source of information respecting the relations of these canals to the rest of the 

 economy is wanting. We may be allowed, however, to presume that these passages are 

 analogous in function to the openings of other kinds which are found, affording communi- 

 cation apparently between the polypide-cell and the circumambient water in many other 

 cases, such as the canals which lead from the bottom of the cells to the under surface in 

 several species of Cupularia and Lunulites, the pores and openings of various kinds in 

 numerous species of Eschara, Lepralia, &c. ; and, to come to nearer allies, to the minute 

 pores which exist in the walls of the cells in all the Crisiidae, Pustulopora, Jdmonea, &c., 

 but more particularly to the perforations which are so manifest both in front and behind 

 in the Hornera. In fact, in transverse fractures of some species of this genus, minute 

 tortuous canals may be traced from the smaller pores on the anterior surface into the 

 interior of the branch ; resembling, except in their diminutive size and paucity of 

 numbers, the interstitial canals of Heteropora. This view of the nature of the inter- 

 stitial canals is further borne out by the circumstance that in one or two of the species 

 here referred to Heteropora, for want of a more eligible situation, the small size and 

 comparative fewness of the ostioles and passages, conjoined with a strongly marked 

 disposition to reticulation on the surface, a close approach is made to Hornera. 

 Heteroporae of this kind are represented by H. reticulata. 



1 ' Miocene Fossils of N. America,' Q. J. Geol. Soc., vol. i, p. 500, 1845. 



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