Corals dredged by H.M.S. ' Challenger/ 561 



Dimensions : of an adult specimen — extreme diameter 1*7 centim.. ex- 

 treme height from the summit of the columella to the centre of the base 

 7 millims. ; of the young specimen — extreme diameter 6 millims., height 

 3*5 millims. Three adult dead specimens and one living young one were 

 obtained. 



In the development of a flower-like series of oval chambers around the 

 elongate columella, this coral most strikingly resembles StepJianophyllia 

 jlorealis of Quenstedt, which is a fossil of the "White Jura" (= Oxford 

 Clay) formation. The oval chambers here in the first series around 

 the columella are twelve in number, and alternate with twelve in the 

 second series. In S. eomplicata, six alternate with six. In S. Jlorealis 

 there appears to be no trace of the bisection of these chambers by the 

 straight primary and secondary septa as in S. eomplicata ; but the fossil 

 specimens are, according to Quenstedt, always so much mutilated that 

 their structure can only partially be made out. Possibly the twelve 

 chambers of S. Jlorealis may represent the twelve of S. eomplicata, formed 

 by the bisection of the six inner by the primary septa, which might 

 appear as figured in S. Jlorealis in much-worn specimens. Comparison 

 with actual specimens will determine this point. In S. Jlorealis forty- 

 eight septa only are distinguishable ; but it is highly probable that 

 structures so slight as the quinary septa of JS. eomplicata might be 

 indistinguishable in a mutilated fossil. The coral appears to fall into 

 that division of the Stephanophyllias distinguished by Milne-Edwards 

 as having the secondary septa smaller than the tertiary, and in which 

 the tertiary septa fuse together in front of the secondary, which do not 

 reach the centre. The coral, in fact, resembles S. sueciea, a fossil from 

 Ignaberga, Sweden ; but in this coral the columella is rudimentary. On 

 the other hand, Quenstedt's S. Jlorealis has been supposed by Milne- 

 Edwards to be Turbinolid, and allied to the genus Thecocyathus. 



Stephanophyllia formosissima, sp. n. 

 The corallum is discoid, with the base flat in the centre and slightly 

 curved towards the margin. It is white and very light and fragile, much 

 more so than in S. eomplicata, being composed of a fine trabecular net- 

 work, through which the light penetrates freely, as through a fine sieve, 

 when the coral is held up to the light. The base is composed of a series 

 of fine, radiating, costal rods connected by transverse trabecule, which 

 have a general concentric disposition. The septa are composed, like the 

 remainder of the corallum, of fused trabecule; but these are stouter than 

 those composing the base, and more perfectly fused, so as to form, in 

 most regions, continuous plates pierced by rounded perforations. There 

 are six systems of septa and five cycles. The upper margins of the septa 

 rise in a curve from points distant a short space from the margin of the 

 calicle, and, ascending to some height above the level of the base, sink 

 down again internally to the wide, oval fossa occupied by the columella. 



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