Reprinted from the " Bulletin, Liverpool Museum," I. 



CRAB-GALL ON MILLEPORA. 



By Sydney J. Hickson, M.A., E.R.S., Beyer Professor of Zoology, 

 Owens College, Manchester. 



With Plate XL 



The occurrence of gall-like growths on certain genera of branched 

 Zoantharian corals, belonging to the genera Sideropora, Seriatopora, 

 and Pocillopora, has been known to zoologists for many years. The 

 best description of them may be found in Semper's interesting book, 

 "The Natural Conditions of Existence as they affect Animal Life." 1 



The Crab that causes the growth of the gall is called Hapalocarcimis 

 marsupialis. These galls are by no means rare. In nearly every 

 Museum which possesses several specimens of these genera, examples 

 of such galls are sure to be found ; and in Seriatopora itself as many 

 as nine or ten galls in different stages of formation are frequently seen 

 in specimens less than a foot in diameter. 



The occurrence of Crab-galls on Millepora, however, has not, I believe, 

 been hitherto recorded. It must, however, be of extremely rare 

 occurrence, as it has never before come to my notice. During the past 

 ten years I have examined the whole stock of Millepores in several 

 Museums, and have received for examination from naturalists in 

 various parts of the world the specimens of this genus that they have 

 collected. I have noted the various parasites and commensals that are 

 found on them, and the many variations and distortions of growth that 

 they exhibit, and, therefore, have good reason for saying that the 

 occurrence is a rare one. 



i Kegan Paul, International Scientific Series, 1881. 



