212 HISTORY OF BRITISH ZOOPHYTES. 



had the progress of its growth stopped by some impending 

 rock or other accident, part of its upper branches appearing 

 as if cut off in a horizontal direction. This, we observe, 

 has diverted the course of the animals back the way they 

 came, so that we find many of the lately-formed cells covered 

 over and confused with an irregular appearance of the cal- 

 careous matter. This we can perceive, as far as we can 

 trace the animals back in their retreat ; and upon taking off 

 the calcareous matter, we find that the horny substance, 

 which they had deposited since their return, had filled up 

 most of the vacant places in that part of the reticulation." 



Genus XX. PRIMNOA, Lamour. 



Gen. Char. Polypidom plant-like, irregularly branched; the 

 axis horny, becoming very hard, continuous; polype-cells pro- 

 truded far beyond the crust, subpedunculated and moveable, 

 squamous ; the aperture furnished with eight smaller testaceous 

 scales. Johnston. 



1. PRIMNOA LEPADIFERA, Professor Jameson. 

 Hab. Coasts of Aberdeenshire and Shetland, Jameson. 

 "The axis, when young, is corneous, but in the older 

 branches it is like bone. The flesh is covered with minute 



