THE SPECIES OF THE GENUS MILLEPORA. 141 



a range as may be seen on different parts of a single piece 9 and 4, 

 and 8 and 3. 



On the basal incrusting regions of a specimen of Millepore in the 

 Manchester Museum I have observed several widely-separated gastro- 

 pores attended by only one, two, or three dactylopores, and a similar 

 paucity of dactylopores I have more recently noticed in specimens from 

 the collection made by Mr. Gardiner in Funafuti and Rotuma. 



I may point to the figures obtained from an examination of the 

 specimens of M. alcicornis given to me by Mr. Lister to show the 

 variability of this feature in the colony. 



The specimens were a number of broken branches, each a few inches 

 in length, beautifully preserved in spirit. Two specimens were taken 

 at random and twelve cycles counted on each. The average of one 

 came out 6 "7 dactylozooids to each gastrozooid, and of the other 5 "08 

 dactylozooids to each gastrozooid. 



The only author who has referred to the number of dactylopores in 

 each cycle is Moseley. He says that each group consists " of a 

 centrally placed gastropore surrounded by a ring of five, six, or seven 

 dactylopores," and on counting the number of dactylopores in each 

 cycle that are drawn in Mr. Wild's picture in Moseley's ' Philosophical 

 Transactions ' paper I find that the average is 6. 



In Milne-Edwards and Haime's figure of M. intricata there are 5 

 gastropores to 35 dactylopores ; of M. verrucosa, there are 7 gastropores 

 to 32 dactylopores (?) ; in M. tuberculosa, 5 gastropores to 18 dactylo- 

 pores ; but it is not certain that these figures can be absolutely relied 

 upon. They are, however, on the whole, very similar to my own 

 results. 



The general conclusions, then, that must be drawn from these obser- 

 vations are : — 



That the number of dactylopores in each group is very variable in 

 each individual colony of Millepora. There may be, in fact, any num- 

 ber up to 8 or 9. 



That specimens of widely different forms of growth have approxi- 

 mately the same average number of dactylopores in each group. 



That the average number of dactylopores, in each group for 

 specimens of all kinds is about 6. 



That the average number of dactylopores to each gastropore cannot 

 be used as a specific character. 



