BAH AM AN PORITES. 77 



In addition to this there are three other specimens, all showing essentially the same 

 characters, such as the steeply convex eminences and general calicle structure, though, as a 

 rule, with thinner walls. 



Specimen h, also from the Bahamas, encrusting a piece of a glass bottle, but without nearer 

 locality, has the same characters as to growth, shape of humps on the surface, and the position 

 of these, this is, in the central region. The walls differ in being much simpler. A slightly 

 zigzag median thread forms a keel, from each side of which the short septa slope slightly 

 down, and then descend vertically round the large deep fossa. Wliere these walls thicken 

 they form a stout filamentous network, the nodes of which rise up over the sui-face as short 

 blunt processes. PI. IV. fig. 5 is taken from the thin expanding edge, where it creeps over 

 the smooth glass. 



h. Encrusting a piece of bottle. Zool. Dept. 86. 10. 13. 11. 



c (PI. IV. fig. 6) has the same keeled walls as h, but the columellar tangle is more open, 

 and consequently looks deeper, and there is frequently a central tubercle visible. 



The stock is differently grown. It appears at one time to have encrusted a smooth surface 

 like that of a bottle, but having apparently been unable to spread laterally, successive gi-owths 

 have built up a tall narrow ridge. From some unrecorded locality, but presumably belonging 

 to this group of Bahama specimens. 



c Zool. Dept. 91. 1. 16. 1. (part). 



rf is a small rounded knob showing a median keel along the walls. The septa have a 

 tendency to be knobbed like the typical septal granules of the Indo-Pacific forms, and within 

 them traces of pali with a large central tubercle appear in the fossa. 



This again, has no locality, but the Eegister No. shows it was acquired with c. It is 

 associated with a fine specimen of Diploria, which is a well known West Indian coral. 



a Zool. Dept. 91. 1. 16. 1. (part). 



e. Underneath the stock a is a small encrusting patch, apparently of a very different 

 Porites, with very shallow calicles ; the flattened walls being a zigzag of narrow, angular, 

 skeletal threads, from which nodulated, bent, and angular septa project. The fossa seems 

 filled up with irregular skeletal elements, among which pali may be recognised. 



But for the tendency to produce saw-like septa, seen in specimen «, showing as knobs in 

 specimen d, I should have classed this separately, though with the evidence for the changes 

 which position and accident can produce in specimen a, it is safest to regard this as a young 

 colony growing in a very unfavourable position. 



e. Growing on a. 



Observation. — Fi'om Mr. Rathbun's Catalogue * we note that specimens called asirmoides, 

 clavaria, and fitr cat a, from the Bahamas, are preserved in the United States National Museum. 

 The astrceoides-\ike specimen is from Nassau, and might, perhaps, be the same as a. A com- 

 parison is desirable. 



* Proc. U.S. Nat. Museum, x. (1887) pp. 354, 356. 



