58 ZOOLOGY. 



ramifications. The whole canal system is connected to- 

 gether by a freely anastomosing mesh-work of smaller ves- 

 sels, and communicates freely by numerous offsets with the 

 cavities of the calicles." As the animals increase in num- 

 bers and die, the coral stock increases in size, the layer con- 

 taining the living animals forming a thin film only, the 

 bottom of the little cups or pores forming a table or plat- 

 form, whence the term Tdbulata, originally applied to this 

 group, the old calicles being divided by a series of trans- 

 verse plates or laminae, separating them into series of cham- 

 bers. Moseley shows that the corallum of Millepora is dis- 

 tinguished from all other coralla by its systems of canals 

 branching in an arborescent manner, while the tabulate 

 structure occurs in certain Alcyonaria, Zoantharia, and in 

 other Hydroida ; hence the group Tabulata, as previously 

 stated by Verrill, is an artificial one. 



The animals of the Millepora are of two kinds ; those in- 

 habiting the central cup or pore are short, thick zooids, 

 with a mouth and four tentacles, and only half a milli- 

 metre in height ; those in the smaller pores are longer and 

 slenderer, about one and a half millimetres in height, with 

 from usually five to twenty tentacles, situated at irregular in- 

 tervals from the base to the summit of the body. The body 

 cavities of the zooids end in blind sacs at the uv/otom of the 

 cup, but are continuous beyond with the canals of the hy- 

 drophyton, the latter being defined by Allman as forming 

 in the Hydroids " the common basis by which the several 

 zooids of the colony are kept in union with one another/' 

 As we know nothing of the mode of reproduction of Mille- 

 pora, we must leave it for the present near Hydractinia, to 

 which the adult animals are nearest related. Moseley also 

 discovered that Sty laster, a beautiful pink coral which grows 

 at Tahiti, with the Millepora, is in reality a Hydroid, and 

 not a true coral polyp, as has always been supposed. That, 

 finally, Millepora is a true Hydroid is proved, Moseley thinks, 

 by the peculiar structure of the hydrophyton, the forms of 

 the zooids, the absence of all trace of mesenteries, the ap- 

 parent septa present in the tentacles, and by the presence 

 of thread-cells of the form peculiar to "the Hydrozoa. The 



