68 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



2. Idmonea contortilis Lonsdale. Sp. n. 



a. Branches natural size. 



b. Portion of the same magnified, and exhibiting the contorted mode of growth. 



c. Part of a branch more highly magnified, to show the pores in the surface. 



d. Magnified portion of the reverse side (e. nat. size), exhibiting the range of 

 the tubes, exposed by fracture. 



Branches compressed, bifurcated, contorted and anastomosed ; 

 tubular openings projecting, variously grouped ; no marked, con- 

 tinuous, central line between the groups ; reverse surface slightly 

 convex, furroived transversely, and streaked faintly by the separat- 

 ing walls of the tubes. 



In the absence of the central line or medial ridge, and of a 

 regular bilateral arrangement of the tubular openings, this coral 

 differs from the generic characters of Idmonea as given by Lamou- 

 roux (Exp. Methodique, p. 80.), and repeated by Milne Edwards 

 (Ann. Sc. Nat., 2d series, vol. ix. Zool.) ; but it agrees in the 

 general distribution of the openings with the latter author's en- 

 larged figure of Idmonea transversa (loc. cit. PI. ix. fig. 3. ; like- 

 wise Recherches sur les Polypes ; Memoire sur les Crisies, &c.) ; 

 De Blainville also, in his description of the genus, says, the open- 

 ings are disposed "en demi-anneau ou en lignes brisees" (Man. 

 d'Actinol., p. 419.). There is a slight resemblance between the 

 Timber Creek coral and the Cellepora echinata of Goldfuss (Pe- 

 tref. xxxvi. f. 14.), an Astrupp tertiary fossil, but which is said 

 to be attached to a Terebratula. 



The branches are slightly convex on both sides (see figures), and 

 so greatly contorted that the reverse surface of some portions of a 

 specimen are completely turned round. The tubular openings 



