14(3 ME. H. M. BERKAED ON EECEKT POEITIDJE. 



the term is quite iBconsistent with the original description, where 

 the trabeculse are said to have " I'aspect de petites tiges iioueusei!, 

 etranglees d'espace en espace " *. The septal teeth of Montipora 

 do not conform to this description, while the vertical rods in that 

 same genus and in For lies, as a rule, do. 



Por the future, however, the word " trabecula " represents 

 merely so much formative tissue, and, if it and its adjectives are 

 retained at all, they can only have descriptive significance. Their 

 intrusion into the morphology of the Madreporaria has so far 

 only led to confusion. 1 must again, therefore, express my con- 

 viction that the more esact description of the trabecula given us 

 by Miss Ogilvie is solely of histological importance, and cannot 

 again give it any weight as a morphological unit. 



Returning, however, to the genus Montipora, my researcbes have 

 led me fully to endorse the widespread opinion that it belonged 

 to the Madreporidae, and not to the Poritidse. A comparative 

 study of their skeletons showed them, as I thought, to be quite 

 distinct. It is therefore not without interest to note that the 

 conclusion we have now arrived at as to the origin of JPorltes has 

 once more brought them in a manner together. Both may be 

 called Madreporids in which the polyps are fixed at a very low 

 stage of development, but the processes in the two cases are in 

 strange contrast. In Porites the whole organization, polyp and 

 skeleton, never gets beyond the early stage at which their 

 development is arrested. But, in Montipora, the dwarfing of the 

 polyps seems to have been due to the excessive development of 

 the skeleton as such. The Madreporarian skeleton, in fact, 

 reaches its highest level of specialization in this genns, though 

 at the expense of the polyps. The dwarfing of the polyps iu the 

 two genera gave some colour to the classification which placed 

 them in the same family. Indeed, forms occur in both genera 

 which it is not easy at first sight to assign to the one or to the 

 other. Milne-Edwards's distinction, that one has an interstitial 

 ccenenchyma and the other has not, does not hold good, for there 

 are many Forites with such thick walls that no dift'erence in 

 this respect can be recognized. The real distinction is found in 

 tbe calicles. The septa of Jfow^zjporff, composed of six vertical 

 rows of iSmall horizontal teeth round a deep fossa, are unknown 



* 'Les Coralliaires,' toI. i. (1857) p. 32. 



