120 Mr. W. S. Kent on a neio Genus of Madreporaria. 



between the sponges and the other Coelenterata. This boun- 

 dary appears to be very artificial, if we consider that both 

 among the Vermes and among the Mollusca there are parti- 

 cular forms with urticating organs. It is, however, still 

 further weakened when we take a general view of the whole 

 of the conditions of histological differentiation in the sponges 

 and corals, and become convinced that in both classes a wide 

 scope is given to the degree of differentiation. Not a few of 

 the more highly developed sponges, with regard to histological 

 differentiation, perhaps occupy a higher grade than many 

 corals, or at least than the Hydrce among the Acalephs. On 

 the other hand, a very important and thoroughgoing difference 

 between the Acalephs and Sponges would result from the 

 confirmation of the supposition expressed by me above, that 

 zoospermia and consequently sexual differentiation do not 

 occur among the sponges, and that the supposed " ova " of the 

 sponges are agamic spores. 



The further ex])lanation and establishment of all the parti- 

 culars here brought forward I reserve for my detailed mono- 

 graph of the Calcispongiffi, and, in conclusion, beg all readers 

 of this preliminary communication who may be in possession 

 of dried or spirit specimens of Calcispongias to be kind enough 

 to transmit them to me for examination and comparison, in 

 order to render the systematic part of that work as complete as 

 possible. The Calcispongiaj have hitherto been so sparingly 

 represented in zoological collections almost everywhere, and 

 their classification is so imjierfect, that the following Prodro- 

 mus of a system of the Calcispongias must commence quite 

 afresh. Moreover many Calcispongiae are so very different in 

 their internal structure, whilst their sober exterior appears 

 almost the same, that the most accurate microscopic examina- 

 tion of all the forms hitherto discovered is quite indispensable 

 for the establishment of their classification. 



XIV. — On a neiv Genvs of the Madrejyoraria or Stony CoroJs 

 (Stenohelia). By Wm." S. Kent, F.Z.S., F.R.M.S., of the 

 Geological Department, British Museum. 



In the ' Proceedings of the Zoological Society for 1862,' 

 p. 196, J. Y. Johnson described as a new species oi Allopora 

 a small branching coral, of the family Oculinidte, taken by 

 himself in the vicinity of Madeira. There are, however, 

 several points of structure connected with it, seemingly over- 

 looked by Mr. Johnson, which render it perfectly essential 

 that a new genus should be created for its reception. 



