28 MADREPORARIA. 



Species 4. Turbinaria laminata. (ri. IV. ; V\. XXXI. fig. 3.) 



Description. — Corallum an open cup, edges tending to curl outwards and downwards, 

 margin thin and externally wrinkled. Stalk thin. 



Calicles evenly distributed, crowded, somewhat more than their diameter (2 mm.) apart ; 

 immersed in level coenenchyma or else with the thin regular elliptical margin slightly raised, 

 in which case the surface sinks into slight valleys between rows of calicles or between 

 individual calicles, which latter then appear to protrude. Septa 18 to 24, thin and delicate, 

 descend with a very slight downward curve (concave upwards) to the columella, which is thus 

 nearly on a level with the margin of the calicle. The columella is an open reticulum of the 

 thin septal plates, is irregular in shape, and fills up about the half-radius circle. The inter- 

 septal loculi are conspicuous, owing to the delicacy of the septa ; sharply bounded peripherally, 

 short, to long, petaloid. 



The ccenenchyma is built up of flat, porous laminae parallel with the surface, this character 

 appearing even in the reticulum of the growing edge. Over certain areas, especially in 

 regions where the calicles are all immersed, and to a less extent in the valleys between the 

 calicles, the pores are so numerous that the corallum has a blackish look. Elsewhere, in 

 regions where the corallites tend to rise above the surface as round protuberant calicles, the 

 laminte are less porous, and smooth and white, making the corallum look stony. The 

 laminate character of the ccenenchyma is very marked externally. 



There is only one Turbinarian in the Collection with the ccenenchyma developed as in this 

 type specimen. There are, however, two other specimens which seem to tend that way, as 

 indeed, does the young cup which I have already associated with the last type, as probably 

 its early stage. The two specimens referred to are united here with this type chiefly on 

 account of the stony character of the ccenenchyma, which is here and there laminate, but 

 largely also a ridge-and-furrow system. Again, their calicles differ in having a definite oval 

 fossa surrounded by a ring of vertical septa, the absence of such a fossa being a marked feature 

 in the type. On comparing all the specimens of this and the last type, there can be little 

 doubt that they are all related forms, wMle no two specimens could be less alike than are the 

 type specimens themselves. 



a. Locality not recorded. [Register No. 46. 7. 1. 9.] (Type.) 



? h. Locality not recorded. [Register No. 41. 1. 13. 38.] 



This latter is a thin, open cup, with somewhat more protuberant calicles, which are 

 smaller, with sharp, protuberant elliptical margins. It appears to belong somewhere between 

 this type and the young specimen attributed to the last. 



? c. Locahty not recorded. [Register No. 93. 7. 1. 5.] 



This is a distorted cup, very deep, and flattened so tliat the two opposite edges nearly 

 meet. The calicles here are larger and slightly more protuberant. 



