CLASSIFICATION. 13 



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

 present. The living animal of Millepora was first examined 

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

 nounced it to be a Hydrozoon, allied to Hy dr actinia ; but its 

 anatomy was first thoroughly studied and worked out by Mr 

 Moseley (Phil. Trans., vol. clxvii. 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 alcicomis, of the natural size; B, 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 (f, c 1 } 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 HydrocoralliiuB. 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 polypites, each of which pos- 

 sesses four tentacles, surrounding a central mouth, which opens 

 into the gastric cavity of the zooid (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, 



