44 MADREPORAKIA. 



a sliu'lit j,'n>t'iiisli tint. The tentacles are red, tliough yellow at the tips, and with a black spot 

 at their extremities, suggestive of an aperture. 



Though this is a thin expanding form, it has always been regarded as one of the more 

 massive astrmaides of Authors (see Table III. P. and remarks.) 



24. Porites Guadalupe 4. (/'. Ovadalnpensis quarta.) (PI. XI. fig. 5.) 

 [Guadalupe, coll. Duchassaing ; Paris Museum.] 



Description. — The corallum rises as a compact cluster of erect, stout, slightly sinuous 

 and gradually thickening lobes of different thicknesses, which slightly flatten and divide at 

 small angles ; only the swollen rounded tips of the lobes are alive for about 2 cm. 



The calicles are about 1-5 mm. in diameter. At the tips they open flush with the 

 surface in a very delicate lamellate reticulum, the septa being thin wavy lamellae joining a 

 columellar tangle level with the surface. Below this tip the walls rise as thin, regularly 

 zigzag membranes above the septa and columellar tangle. Below this again the trabecular 

 elements of the walls rise high as tall bristles and flattened spikes, wliile the intervening 

 membranous portions are developed only intermittently. Stray spikes and plates represent 

 the septa. The surface is thus coarsely hirsute. At varying depths a straggling reticulum 

 can be seen from which a few tall pali arise, sometimes in a compact cluster with the 

 columellar tubercle, at others with a deep, open, central fossa. Before dying down and being 

 covered over by the epithecal film, the calicles tend to flatten down again and the columellar 

 tangle to rise with a central rosette of 4 to 5 gi-anules as pali and a central tubercle. 



The colour of the unbleached coral, which is about 13 cm. liigh, is a reddish buff. The 

 bristly surface sometimes shows through the epithecal film. 



This description is based upon a specimen in the Paris Museum (No. 196a) labelled 

 " rorites valida, M. Duchassaing — Guadalupe." In the supplement to " Les Coralliaires des 

 Antilles," p. 94, PI. X. fig. 13, tliis author in conjunction with Michelotti, described and 

 figured a specimen from St. Thomas (occurring also at Tortola), which they called Porites 

 valida (see p. 56). A comparison of their description of that coral with the above shows 

 them to be quite difi"erent corals. The extraordinarily bristly surface shown in this coral by 

 the upgrowth of the trabecule of the walls is too remarkable to be overlooked. It is true 

 that the St. Thomas coral is said to have denticulate walls, but that word is quite inadequate 

 to describe the condition above noted. Further there is said to be no columella in the 

 specimen from St. Thomas ; there certainly is in this specimen, though here and there the 

 fossa is open. 



This growth-form is of interest and may be compared with that of others, c.f e.g. 

 P. CuroA^oa 2; see also Table III. p. 136. It represents the type with gradually thickening, 

 usually slightly sinuous stems, which, of all others, deserves the name "c/amria," if that 

 name is to be used in its descriptive sense, see the Historical Sketch, p. 3. 



