Study of Madreporarian Types of Corals. 223 



and these he called " j»seMcfo-synapticulfe." The name of 

 " true synapticulfe " he limited to such as were formed around 

 new centres of deposit out of the septal plane; these he found 

 in Siderastraea, but did not farther examine typical genera 

 belonging to the families Fungina? and Lophoserinas. The 

 author's results are that pseudo-synaptfculce occur not only in 

 Thamnastrffiinre, but also in the Funginge, Lophoserinse, and 

 occasionally in Astrreidas and Eupsammida? ; while true 

 synapticnke occur chiefly in Funginge and Eupsammidce, 

 rarely in Lophoserin*, and never in Astrasida?. The author 

 regards true synapticula? as basal structures representing 

 modified dissepiments. The advantage of synapticulfe to the 

 polyp is that they afford a basal support over which the fleshy 

 parts and mesenterial loculi may bend and be continued to 

 some depth. The author, in pointing this out, refers to the 

 analogy of the internal canaliculate visceral system thus pro- 

 duced with the external canaliculate system attained by a 

 porous ccenenchyme in " Perforate " colonies. At the same 

 time she thoroughly disagrees with the prevailing opinion that 

 the synapticulate types have any nearer relationship with 

 lladrepora, Porites, &c, since the skeletal parts show many 

 important differences of structure ; neither is the " porous 

 ccenenchyme " in any way homologous with the synapticulate 

 calyx. 



No essential difference is presented between septa, costas, 

 and wall in respect of their microscopic structure ; and the 

 author found it also for other reasons practical to distinguish 

 in her work the septa and costse under the inclusive name of 

 radial structures, the wall, on the other hand, as a tangential 

 structure. Dissepiments, tabula?, true synapticulaj, and certain 

 kinds of columella are regarded as basal structures. 



The microscopic structure of dissepiments and tabulce is 

 demonstrated by the author to be the same. Both are composed 

 of a series of calcareous growth-lamella? laid down from one 

 surface only of the aboral body-wall of the polyp. The fibro- 

 crystalline deposit is therefore perpendicular to the plane of 

 contact between polyp and skeleton. The distance from one 

 platform of dissepiments to the next above coincides in all 

 typical Astrseids with the interval between two growth- lines 

 on the septal surface. It may be deduced from this that the 

 polyp lays down a new basal support for itself at the close of 

 each growth-period. The solid calcareous deposit (usually 

 called " stereoplasm " or " endotheca ") at the base of the 

 short simple calyces of most Turbinolids has the same micro- 

 scopic structure as tabula? or dissepiments, differing from 



