16 Mr. J. J. Qaelcli on some 



pored openings, closed bj thin membranous tissue and placed 

 between the ridges, leads into the single central cavitj of the 

 ampulla. 



Locality. Raratonga. B.M. 



Two specimens of this beautiful form were presented 

 to the national collection by Prof. Flower. I have been 

 enabled to describe this species through the courtesy of 

 Prof. Charles Stewart^ who first remarked its specific di- 

 stinctness. 



A very fine specimen in the museum of the Royal College 

 of Surgeons agrees most closely, except in the characters of 

 its ampullae, with this species. These ampullse are raised 

 and confluent, the individual ampulla being undistinguishable 

 in the mass. Their surface is covered by the conical 

 markings characteristic of the coenosteum, and is irregularly 

 and rather sparsely pored with minute openings. This form 

 of the ampuUge is constant throughout the stock, while that 

 described for the species is constant on the two stocks in the 

 British Museum. I am strongly inclined to think that these 

 confluent ampullate swellings are the forms characteristic of 

 the later stages of the ampullse of the male stocks, which in 

 the earlier stages are sunk beneath the surface of the coenos- 

 teum. This seems to me borne out by the fact that in a 

 large series of specimens of D. violacea in the national col- 

 lection the two forms of the ampullae are present — the one with 

 the stelliform much swollen eminences, which, though grouped 

 together, are distinct from each other, and are bounded by an 

 outer circle of pored openings j the other with smaller 

 swellings, in which separate ampullae are seldom distinguish- 

 able, and having scattered minute pores over the surface. 



This species, though close to D. granulosa^ differs from 

 it in many particulars, of which the crowded corymbed mode 

 of growth, the coloration, the smaller and more slender habit, 

 the nature of the surface, the arrangement of its cyclosystems, 

 and the size, position, and form of its dactylopores and 

 gastropores may be cited. 



Distichopora Milesn, Quelch. 



JD. Milesii may be separated from both of the foregoing 

 species bj its very slender regularly flabellate coenosteum ; by 

 the minutely granulated or smooth surface, which is rendered 

 rough and uneven only by the irregular and abundantly 

 developed ampullae j by its dull lake-red or almost crimson 

 colour ; by the very distinct, wide, deep, continuous lateral 



