148 THE VOYAGE OF H.M.S8. CHALLENGER. 
ing the mode of its occurrence, however, it can only be looked upon as a remarkable 
variation in the characters of Madrepora. 
Another curious feature in this same species is the condition of two of the septa in a 
large number of the lateral calicles. Two opposite septa are not only enlarged, as is often 
the case in many species of Madrepora, but become distinctly exsert and sometimes 
considerably so. In other calicles no trace of this exists. 
In many species of the genus more or less marked differences exist between the 
terminal and lateral calicles, but, apart from the suggestive fact that in many species 
no such differences exist, it must be remarked that the terminal and lateral calicles are 
subject to considerable variation among themselves ; so that it does not seem possible to 
regard the terminal polyps as presenting a case of dimorphism. Verrill remarks that 
dimorphism is unknown among the Madreporaria unless the terminal polyps of 
Madrepora be regarded as offering such a case." 
Two important papers, relating, among other things, to growth and budding in 
Madrepora, have recently been published, one by Mr. 8. O. Ridley of the British 
Museum of Natural History,’ and the other by Professor Duncan.’ It seems to be 
clearly established that budding takes place from the walls of the calicles, and not from 
their margin. No case of marginal budding or fission has come under my observation. 
Fifty species of the genus are in the collection. Of these it is probable that some 
will have to be made synonyms of others, for though, from the want of series of 
specimens, it has been impossible in many cases to determine with certainty their 
specific identity or difference, it is evident that many of the forms are very closely allied. 
1. Madrepora securis, Dana. 
Madrepora securis, Dana, Zoophytes, p. 486, pl. xiii. fig. 2. 
Three large fragments of this species were obtained. One, from Banda, is simply an 
erect plate, grown obliquely on one side, the upper margin of which has lost its typical 
quadrate shape and become somewhat trenchant. The calicles, though tubiform, have 
the lower edge much stronger than the upper, and often become rather shortly 
cochleariform, as in Madrepora labrosa. 
Localities. —Banda ; Samboangan, Philippines. 
2. Madrepora cuneata, Dana. 
Madrepora cuneata, Dana, Zoophytes, p. 487. 
A single small specimen and a fragment of this species were obtained. The thick 
lobes which arise from the spreading, incrusting, recurved and contorted plates, are very 
1 Proc. Amer. Assoc. Adv. Sci., 1867, p. 150. 2 Ann. and Mag. Nat. Hist., ser. 5, vol. xiii. p. 284. 
5 Ann. and Mag. Nat. Hist., ser. 5, vol. xiv. p. 188, 
