CLA SSIFJCA TION. 



13 



The smaller tubes are similarly " tabulate." No "septa" are 

 present. The living animal of Millepora was first examined 

 by Professor Louis Agasslz, as the result of which he pro- 

 nounced It to be a Hydrozoon, allied to Hydradinia ; but its 

 anatomy was first thoroughly studied and worked out by Mr 

 Moseley (Phil. Trans., vol. clxvil. p. 117, 1877), who showed 

 that it was In reality the type of a special group of Hydrozoa, 





Fig, I — A, Portion of a mass of Millepora alckornis, of the natural size ; E, Portion of the 

 same, cut open vertically to show the larger tabulate tubes (/, /), and the spongy cceno- 

 sarcal skeleton (c, c), enlarged; c, Small portion of the surface, enlarged to show the 

 larger and smaller openings {p, c') inhabited by the different zooids, and the reticulated 

 calcareous tissue of the skeleton ; D, Part of a polypite, enlarged, showing two whorls of 

 knobbed tentacles. (A, B, and c are after Milne-Edwards and Haime ; D is after 

 Martin Duncan and Major-General Nelson.) 



to which he gave the name of HydrocorallincB. According to 

 the observations of this naturalist, the colony of Millepora con- 

 sists of two kinds of zooids, differing from one another in size. 

 In structure, and In function. The larger zooids — the "gastro- 

 zooids " of Mr Moseley — occupy the larger tubes of the coral- 

 lum, and have the form of short polypltes, each of which pos- 

 sesses four tentacles, surrounding a central mouth, which opens 

 Into the gastric cavity of the zoold (fig. 2, a). Mixed with the 

 " gastrozooids," or surrounding these in definite systems, are 

 more numerous long and slender zooids — the " dactylozooids " 

 of Mr Moseley — which carry numerous clavate tentacles (fig. 2, 



