THE STEUCTFEE OE POEITES. 497 



manent feature of the skeleton. "While I believe it to have beea 

 a primitive element of importance, it is not now uuiversglly 

 developed. I have already mentioned those scattered calicles 

 which occur on most stocks in which the fossa is a deep pit, 

 but, apart from these, we find in very deep calicles that the 

 pali and the columellar tubercle are sometimes wanting. There 

 can be little doubt that there is some correlation between the 

 depth of the calicle and the development of pali. The same 

 phenomenon occurs also in Goniopora. Stocks occur in which 

 great variation exists in the depths of the calicles ; for instance 

 fig. 2, PI. 35, is taken from one side of a stock in which the 

 calicles on the opposite side are much deeper and show only the 

 faintest traces of pali. 



It is not surprising, then, that it is just in the deeper calicles 

 with all septa free, as is shown in diagram 1, that the columellar 

 tubercle is most frequently absent, and the pali often only slightly 

 traceable as faint swellings. But cases are not wanting in which, 

 while the septa are free and the pali hardly traceable, the colu- 

 mellar tubercle is well developed : I have found this in some West 

 Indian species. The combination is interesting, because a Porites 

 without pali but with a columellar tubercle exists in the Berlin 

 Museum, and was named by Ehrenberg P. punctata. Milne- 

 Edwards & Haime first suggested a new generic name for it, and 

 called it Stylareea Mulleri. But these authors suppressed this 

 name the same year and reverted to Ehrenberg's P. punctata. In 

 recent years, however, Dr. Klunzinger* has again revived the 

 genus, re-naming the original specimen Stylarcea punctata, and 

 placing it next to Porites. I find it necessary to add this genus 

 Stylarcea to the list of apparently needless genera given in my 

 previous paper. Eor, not only is there nothing specially startling 

 in the absence of pali and the presence of the columellar tubercle, 

 but, among the many other variations presented by Porites, we 

 actually have specimens in which the columellar tubercle is well 

 developed while the pali are here and there only faintly traceable. 

 As against the advisability of making a new genus on the original 

 specimen of Ehrenberg, I should like to point out that it is so 

 small that, as Ehrenberg suggested, it might easily be a youno- 

 form in which adult conditions are not yet fully developed. I 

 tave frequently observed that young, and perhaps very rapidly 



* Corallentliiere, ii. 1879, which see for other references. 



