56 MADREPORARIA. 



This specimen, judging from the description and figure, is not one of the massive " Porites 

 astramdes " of the West Indies. It is represented as a small, irregularly disk-like patch, with 

 slightly crumpled surface, and .appears to belong to one of the most primitive forms, viz. a 

 small encrusting disk, see Table III. p. 130. It shows some resemblance to a form encrusting 

 a large Mussa, and described below among the Porites from unknown localities (x. 9) ; see 

 p. 117. 



Its long echinulate septa, with only faint traces of the paJic formula, might belong either 

 to a West Indian or to an Indo-Pacific form. 



39. Porites St. Thomas 1. {P. Sancti-Thomoe prima.) 



[St. Thomas and Tortola, coll. Duchassaing ; ? Turin Museum.] 



Syn. Porites valida Duch. and Mich., M6m. surles Cor. des Antilles, Suppl. (1864) p. 94, pi. x. fig. 13. 



Description. — The corallum forms single, stout, raised stems, 20 to 30 cm. high and 3 to 4 

 and more cm. thick, with swollen, slightly flattened tips which fork at wide angles. The 

 living layer seems to cover the whole stem from top to base. 



The calicles are sunk, 1 • 5 mm. in diameter, with thin denticulate walls, and smooth 

 septa, with 3 to 4 sharp, smooth, cylindrical pali. There is no columella. 



This brief description is taken from the original text. But above, on p. 44, under the 

 heading Porites Guadalupe 4-, we have described a very different coral preserved in the Paris 

 Museum, which was also named Porites valida, apparently by Duchassaing himself. A 

 comparison of the descriptions and figures shows that they differ greatly, both in growth 

 (cf PI. XI. fig. 5) and in the characters of the calicles. Porites Guadalupe 4- has a surface 

 remarkable for the erect trabeculse standing up like coarse bristles. There is no mention of 

 this character — and it is too remarkable to have escaped notice — in the text of the author's 

 m^moire written in conjunction with Michelotti. I do not see on what grounds the two can 

 be united under one name. 



There appears to be a slight discrepancy between the author's original figure and his text. 

 The measurements of the stems given in the latter are 3 to 4 and more cm. thick and 20 to 30 

 cm. (" 8-12 pollicaris ") high. The figure, said to be of natural size, shows a specimen about 

 2 cm. thick and about 6 cm. high. 



The mistake is due to the addition of the words " Grandeur naturelle," for, that the 

 specimen was really large, we may gather from the name " valida." 



This Porites is quite unique so far as the records go, quite as unique as are those 

 described and figured by Lesueur (P. Nevis Island and P. St. Bartholomew 1). The lumping of 

 them all into one or two species is simply the negation of classification. 



