58 MADREPORARIA. 



in number. The columellar tangle is always visible, but the central tubercle, which is also 

 echinulate, is sometimes absent. 



This description is based upon notes made in the Paris Museum on a specimen Z 194a, 

 and labelled " Porites Solanderi, St. Thomas, M. Duchassaing." It seems to agree fairly with 

 the very brief description given in the original text, and also with the specimen ia the Turin 

 Museum, regarded as the type of P. Solanderi, \). and M., a magnified photograph of which 

 was kindly prepared for this Catalogue by Count Peracca, see PI. III. fig. 4. The coral was 

 apparently given this name by M. Duchassaing, because of its supposed resemblance to that 

 figured in Ellis and Solander's Zoophytes, pi. xlvii. fig. 1. This synonymy, suggested in 

 the original work, is not repeated in the supplement. I find in my notes that the specimen 

 has certain striking resemblances with P. Guadalupe 3, only the trabeculie do not stand up 

 like tall bristles. The resemblance suggested is, I think, delusive, and rests upon the shape 

 of the blanches and the ragged denticulate walls. They may, however, be related more nearly 

 than simply as members of the same genus. 



It should be remembered that the figures of the calicles here given are from the Turin 

 specimen, while the growth-form is that of the Paris specimen, which we have assumed to be 

 of the same kind. 



42. Porites St. Thomas 4. (P. Sancti-Thomce quarta.) (PI. III. fig. 5.) 

 [St. Thomas, coll. Duchassaing and Michelotti ; Turin.] 



Syn. Porites plumieri Duch. and Mich., Mem. siu- les Cor. des Antilles Suppl. (1864) p. 96, pi. x. 

 fig. 14. 



Description. — The corallum rises as round, slightly swelling stems, which fork dichoto- 

 mously, the prongs tending to bend in towards the vertical in slight curves. Of each pair of 

 prongs that furthest from the axis seems oftenest to abort. This causes the stock to rise 

 rapidly in height, with here and there a few lateral branches of different sizes. When clusters 

 of these stems rise side by side, their branches seem to fuse freely. The living layer seems to 

 extend indefinitely downwards over the stock. 



Calicles everywhere superficial, slightly over 1 mm. in diameter but very irregular in 

 size, snb-circular or polygonal, with sides of very unequal lengths. The walls are thin, 

 incomplete, and show only faint traces of any zigzag arrangement of the connecting lines which 

 vary greatly in thickness, here thin and there thick. The septa project from the walls very 

 irregularly, both as to thickness and length ; the irregularities being doubtless due to their 

 being very perforate. In every calicle one or more may be seen united with one or more of the 

 pali ; but for these unions with the septa, the pali rise to the surface mostly as separate 

 granules, although other imions both with one another and with a small central tubercle can 

 be traced deeper down. The five principals are always present, and for the most part they 

 surround a deep central fossa. The septa and granules, either septal or paliform, are mostly 

 frosted or finely echinulate. 



This description is based chiefly upon the figure given by the authors, and upon the 



