U4 MADREPORARIA. 



the Museum are practically complete except where the wall-edges have been altered by 

 aqueous action, or rubbed down by rolling. The rest of Milne-Edwards' description agrees 

 fairly well. It is not correct that the innermost septal spines are always the longest, some- 

 times those near the calicle aperture project furthest ; nor is the columellar tangle papillose, 

 but a smooth thick coil as described. 



This is one of the Goniopora; whose texture is essentially lamellate, reminding one of a 

 group of Paris Basin forms, of which G. Paris Basin 1J/. is specially remarkable. It may be 

 noticed, however, that the Paris Basin forms which were attached to other ('vegetable) 

 organisms showed an entirely different calicular structure (see G. Paris Basin 4)- 



There are two specimens, one identified by Martin Duncan as Litharata desnoyersi, and 

 the other transferred from the Museum of Practical Geology in 1880. 



a, 6. Geol. Dept. E. 2012 and R. 4827. 



139. Goniopora Coutances (2 )2- (PL X". fig. 2.) 

 [Hauteville, Coutances, La Manche (Middle Eocene) ; British Museum.] 



Description. — Corallum encrusting, convex, with its thin lateral edges tending to envelop 

 loose objects growing under them. 



Calicles 3 mm. across, about 2 mm. deep in the highest central parts. The walls show 

 very irregular wall-threads or membranes, zigzag, and bent and twisted so as frequently, with 

 the forking and bending of the septa, to form an open-meshed flaky reticulum. The membrane 

 is very porous, with openings quite irregular in shape and position. The septa, which do not 

 project far into the calicle, are also perforate membranes ; they are very irregularly twisted 

 about, with spiny edges which are bent from side to side, obscuring the radial symmetry and 

 forming together an incomplete, very jagged, flaky reticulum on the inner sides of the walls. 

 The columellar tangle is an open large-meshed coil of thin filaments and flakes. 



A glance at the figure will show the extraordinary skeletal structure of this coral. It 

 clearly belongs to the Paris Basin group characterised by the smooth lamellate texture of the 

 skeleton (compare, for example, G. Paris Basin 9, 10 and llj). But here the waviness of the 

 walls and septa have reached an extreme. 



The clearing away of a portion of the sand grains entangled in this complicated mem- 

 branous reticulum, which was a necessary preliminary to examination, was very difficult 

 without accidentally detaching portions of the skeleton. Hence the figure does not represent 

 the exact original surface. But there is no reason to believe that that differed very greatly 



from what we can see. 



a . GeoL Dept. R. 4828. 



140. Goniopora France a. m (PI. X". fig. 3.) 



[ ? Paris Basin ; ? Middle Eocene ; British Museum.] 



Description. — Corallum massive. 



Calicles very minute (1 mm.) and inconspicuous. The wall-thread irregularly swollen, 



* On this designation see the prefatory note to Group XIII. p. 154. 



