THE SPECIES OF THE GENUS MILLEPOEA. 143 



rather overgrown by weed, and above, curiously enough, it did not 

 sting, and was the only one in Funafuti that did not." 1 



It is not known whether both the large and the small nematocysts 

 possess the stinging-power, or whether it is confined to only one kind. 

 The small nematocysts are confined to the tentacles of the gastrozooids 

 and dactylozooids, and the large nematocysts, when ripe, occur in the 

 superficial ccenosarc between the pores, but are specially crowded in 

 the neighbourhood of the gastropores. Moseley's description of these 

 features in Millepora is correct for all specimens I have examined. The 

 size and the position of the small nematocysts render them difficult 

 to measure, but the large nematocysts can be scraped off the surface 

 of any preserved specimen in considerable numbers. The average size 

 of these nematocysts when ripe in specimens from Celebes, Bermuda, 

 Bahamas, Funafuti, Rotuma, the Red Sea, Jamaica, and New Britain is 

 exactly the same — - 02 mm. x - 025 mm. The number of the nema- 

 tocysts varies considerably, but as this must be influenced by the 

 manner in which the specimens were killed, and by external conditions 

 affecting them before they were killed, no differences of specific value 

 can be framed from this feature. 



The general anatomy of all these forms is in other respects, as well 

 as those mentioned, so much alike that I know of no means of dis- 

 tinguishing one series of sections of well-preserved material from another. 

 There are no features of the soft parts which indicate in the least the 

 general character of the form and structure of the skeleton they 

 secreted. 



By far the most interesting and in many respects the most important 

 structures of these corals are the generative organs, and to them we 

 should naturally turn for characters which might assist in distinguish- 

 ing species. Unfortunately, however, our knowledge of these structures 

 is very meagre and does not at present help us very much. 



In the specimen presented to me by Prof, Haddon from Torres Strait, 

 I discovered that the male sexual cells migrate into dactylozooids which 

 become converted into medusae. These medusae, when ready to 

 become free, are situated in ampulla?, which are approximately '4 mm. 

 in their greatest diameter: that is, in holes in the skeleton larger than 

 the largest gastropores. In another specimen of a different mode of 

 growth presented to me by Mr. Gardiner from Funafuti I found numbers 

 Extract from a private letter. 



