OCR Text |
Show MR. J. S. GARDINER ON CORA.LS [Dec. 14, Family BOCILLOPORIDJE. I. Genus BOCILLOPORA, Lamarck. Pocillopora, Lamarck, Hist. Anim. sans Vert. ii. p. 273. Pocillopora, Duncan, Bev. Madrep., Jour. Linn. Soc, Zool. vol. xviii. p. 47. The classificatory characters of the species in this genus by means of the corallum are extremely unsatisfactory. In the collections there are over 50 specimens, either whole colonies or brauches from different colonies, and in addition I have examined a very large number of specimens in the British Museum. These show an almost complete series from P. acuta to P. mudreporacea; and any division into subgenera does not seem to me to be admissible, nor do there appear to be any characters running through a limited number of species which will serve to divide up the genus in any way for classificatory purposes. The examination of the polyps in such widely separated species as P. suffruticosu, P. favosa, and P. grandis has failed to show m e any differences in their macroscopic anatomy ; and I am doubtful whether all these so-called species should not rather be described as varieties of one species, the characters of which would be the characters of the whole genus. The growth of the colony is much more vigorous toward the summits of the branches, and to this is clue the angular character of the calices here and their very thin walls. The complete absence of verrucas on the tops of the" branches and their incrassate form in such a species as P. grandis are due to the ends of the branches having reached the low-tide level, and, being unable to grow further upwards, increasing in boih thickness and breadth. Although this is by far the most common species of Madreporaria on the reef at Funafuti, I never found any of its branches with their summits dead, even though they reach almost invariably to the low-tide level. The colonies exhibit generally a very marked growth towards the light, and the under surfaces of horizontally growing branches of clumps are often completely bare of verruca?. The living colonies are usually green or pink when the polyps are expanded, but if retracted are nearly colourless. 1. POCILLOPORA PAUCISTELLATA, Quelch. Pocillopora paucistellata, Quelch, Challenger Eeport on Beef- Corals, p. 65, pl. i. figs. 3-3 a. A few small pieces were dredged which agree well with Quelch's description. The corallum is rather more delicate and branched than the type. The calices are surrounded by short spines, and the primary septa are visible as spinulous projections in some of the subterminal corallites. Funafuti; 5 aud 7 fathoms. |