144 THE CANADIAN NATURALIST. [Vol. vii> 



being due to the bifurcation of each primary septum at a distance 

 of about a line and a-half above the base, and also to the inter- 

 calation of new septa along both sides of a line which runs along 

 the dorsal or convex side of the coral from top to bottom. This 

 line is marked on the exterior by two primary septa, which form 

 a prominent ridge externally and pass inwards to the centre of 

 the coral. At the margin of the cup the septa are somewhat un- 

 equally developed, being alternately larger and smaller, the 

 larger primary septa being prolonged inwards to the centre ot 

 the theca, where they become somewhat bent and twisted to- 

 o'ether. No columella appears to be present, nor are there any 

 tabuloe. The flat sides of the septa are furrowed with a succes- 

 sion of deep grooves, about four or five in the space of one line, 

 which are directed in an obliquely ascending and arching manner 

 from the wall towards the centre, the interspaces between them 

 beino' tumid and rounded, and thus imparting a crenulated ap- 

 pearance to the outer edges of the septa when exposed to view. 

 These arching grooves are not connected with lamellar dissepi- 

 ments having a similar direction ; but the septa for some little 

 distance below the cup are united by delicate transverse dissepi- 

 ments. The epitheca is marked with a few annulatious of 

 o-rowth, which are mostly very obscure, and with well marked 

 costge or strict corresponding with the septa. 



In none of the specimens in my possession does the epitheca 

 extend more than half an inch (often less) above the base of the 

 corallum. Beyond this point to the margin of the calice, the 

 edo'es of the septa are seen with their characteristic ci-enulated 

 appearance, and united here and there by minute dissepiments. 

 As already noted, the flattened convex side of the coral always 

 exhibits two pre-eminently large septa, produced by the bifurca- 

 tion of one, which run from the top to the bottom of the coral in 

 a straight line. The remaining septa are directed obliquely from 

 both sides towards this central pair ; so that new septa are inter- 

 calated along this line in proceeding from the base to the calice. 

 It is possible that these two septa may mark the position of a 

 fosette in the cup ; but none of my specimens exhibit the inte_ 

 rior of the calice, and I am, therefore, unable' to speak positively 

 on this point. For the same reason I can say nothing as to the 

 condition of the free edges of the septa internally. 



The total length of the corallum is from three-quarters of an 

 inch to one inch, the diameter of the calice varying from half aa 



