84 MADKEPORARIA. 



69. Porites West Indies .r. 4. (P. Americana incertw scdis quarta.) (PI. XIII. fig. 4.) 

 [" Les Mers d'Am^rique," coll. Lamarck ; Paris Museum.] 

 Sj'ti. Pmites furcata var. 2 Lamarck, Auimaux sans Vertebras, ii. (1816) p. 271. 



Description. — The corallum rises in stems wliicli tlattcii (lut into tall, thin, erect plates 

 1 cm. thick and less, and much bent. The top edges of the plates divide into fringes of 

 branches which may be either cylindrical and tapering, or else compressed apparently prior to 

 leaf formation and subsequent forking into two or three fresh branches. The leaf edges are 

 about 5 mm. thick ; the forking is at veiy small angles. The living layer extends about 3 cm. 



The calicles are small, about 0*75 mm., slightly depressed. The walls near the top are 

 thin, ragged, and flaky, with a few very irregular, knobbed septa projecting from the edges of 

 the flakes ; the pali are distinct as small granules only gradually forming a ring. Lower 

 down the walls widen, and thin septal ridges rather long and in small groups oi parallel (not 

 radiating) stria; run over the surfaces of the flakes. Where the septa do not thus striate the 

 walls, the latter is covered with distinct granules like the pali, and the whole surface is 

 covered with small, frosted, whitish points standing up above the dead, black, animal matter. 

 In these older calicles the pali are larger and usually six in number, forming a ring round a 

 deep conspicuous fossa. 



This specimen, No. Z 187 « oi the Paris Museum, and labelled as from "Les Mers 

 d' Anacrique," is the var. 2, lohis ultimis coinpressls of Lamarck's Porites furcata. Milue-Edwards 

 and Haime identified it with Dana's Porites conferta, which was the Madrcpora conglomerata 

 of Esper. This coral is discussed below, p. 157, where it is regarded as having been a Goniopora 

 from Madagascar. It would seem that Milne-Edwards, description is founded more upon 

 Esper's figure than upon Lamarck's coral. 



It should be noted that there are no specially West Indian characters about this specimen, 

 and in placing this and some of the following forms luue I am frankly assuming that the 

 words " Mers d'Amerique " apply to the West Indies. 



The black colour of the dead matter on the stock is in contrast with the brown colour of 

 the type, and the point is especially noted by Lamarck that some of the Ibrms are coloured 

 brown and others black by the dead animal matter upon them. 



There seems to be a .second specimen of this same coral in Paris, viz. No. Z 187 c, which 

 has upon it a young disk-like colony, quite smooth and flat, from the middle of which a 

 thin short round-topped digitiform process suddenly rises. This young colony is interesting, 

 because we know so little about the initial stages of these West Indian branching corals, see e.g. 

 P. Barbados 10, p. 42. The flattening and dividing of the tip of this central boss may 

 be the origin of the leaf formation, which is also sliown in this second specimen, only not 

 so marked as in the type because its top edges divide much faster into clusters of digitiform 

 processes. 



