HAPLOPHYLLIA. 51 



For the sake of symmetry, the number of septa has been made equal 

 in all the systems in these diagrams, which is seldom the case. 



Sometimes a small rudimentary septum is seen in each half of the 

 septal fossa on the sides of S- 



Numerous illustrative figures will be found in the plates accompany- 

 ing Ludwig's paper* 



Mr. A. Kunth (Zeitsehr. der Deutsch. Geol '/,.<.. XXL. Heft 3) has also 

 examined the law of growth of the Rugosa, chiefly by the considera- 

 tion of the successive development of the costae. He still adheres to 

 the tetrameral primary division, from want of having examined indi- 

 viduals of very young age. and hence great simplicity. The papers of 

 Romer and of Lindstrom I have had no opportunity to examine. 



In the Bulletin of the Museum of Comparative Zoology. Xo. 7. I 

 referred to the Rugosa, a new genus and species, though with some 

 doubt. I hoped to be able to procure more numerous specimens, par- 

 ticularly as the single one on which the determination rested was not 

 quite normally developed. In this 1 have been disappointed, so that 

 the position of the genus in the system must still remain provisional. 

 The chief ground for placing it among the Rugosa is its general 

 appearance, its smooth ungranulated septa, not resolvable into the 

 regular hexameral arrangement, but ou the other hand difficult also to 

 refer to the modified hexameral system just exposed. 



HAPL0PHYLL1A Pourt. 



Haplophyllia Pourt. Bull Mus. Comp. Zool., Xo. 7. 



Corallum simple, fixed by a broad base, covered with a thick epith- 

 eca : columella styliform, strong, very thick at the base. Interseptal 

 chambers deep, uninterrupted by tabulae or dissepiments, but fi ling 

 up solid at the bottom. 



The nearest known form to Haplophyllia which I have been able to 

 find is Cahphyllum profundum Germ. (Geiuitz) (Astrocyathu& Geirdtsii 

 Ludw. ).f which, however, lacks a columella. It is fossil in the Dyas. 



* There are several points of resemblance in the mode of division of the calicle in the Pocillo- 

 porffi ami in the Rugosa, which would warrant a closer examination ; such are the bilateral sym- 

 metry combined with a more or less marked antero-posterior asymmetry, the shallow calicles, the 

 tabulse, etc. The order of succession of the septa in the I'ocilloporse is not known. 



t I.u Iwig has formed new generic names for nearly all the fossil corals, to adapt them to his 

 classification; such a proceeding can only introduce confusion, particularly as his arrangement is 

 quite artificial. A table of double entry is no doubt very convenient, but unfortunately the organ- 

 ized beings were not created on such a plan. 



