70 



ftll depths to a little beyond low-water mark. The animal^ 

 when expanded, resembles in form the naked Actiniae; when 

 contracted it retires from si«i;ht into the calcareous cup. It 

 is to be found of all sizes from a mere speck to an inch in 

 heifjht. h\ a very young; state it is sometimes found para- 

 sitical on the Alcyonium digitatum, on shells, and the stalks 

 of sea weed ; but as these substances are very perishable 

 in their nature, and ofTer no solid foundation on which to 

 stand, large specimens are never found on them ; on rocks 

 and stones, however, they are frequently large and in great 

 profusion. In the youngest state the animal is naked, and 

 measures about the fifteenth of an inch in diameter and 

 about the thirty-second of an inch in height. In the earliest 

 state in which I Lave seen the calcareous polypidum, 

 there were four small rays, which were free or uncon- 

 nected down to the base; in others I have noticed six 

 primary rays, but in every case they were unconnected 

 with each other. Other rays soon make their appearance 

 between those first formed ; They are mere calcareous 

 specks at first but afterwards increase in size. The first 

 union of the rays is observed as a small calcareous rim at 

 the base of the polype, which afterwards increases both in 

 height and diameter with the age of the animal. 



In taking a review of the polypes of this order, we find 

 that though there is a considerable resemblance in their 

 general anatomy to that of the Asteroid polypes; yet 

 there is also a considerable advance in the complication and 

 elaboration of their various parts. In both there is the 

 radiate form of tentacula, the central membranous stomach, 

 the intervening space between the stomach and sides of the 

 polypes, the dividing the space by longitudinal septa, and 

 one opening serving both for the reception of food and ejection 

 of the undigested remains. In this there are permanent 

 organs set aside for the developenient of ova, forming well 

 defined ovaries ; the structure of the septa and the sides of 

 the animal are of a muscular kind ; and here also are said 

 to be the first traces of a nervous system ; all of which show 

 a considerable advancement on the two preceding orders; 

 and their habits and intelligence also exhibit a correspondent 

 elevation. 



The comparative smallness and simpleness of the only 

 calcareous species of our shores, has not allowed many 

 observations to be made on the vitality or non-vitalily of the 

 polypidom. But few as they have been they greatly affect 

 the question. In young specimens the polypidoms are very 

 small and increase in size with the age of the polype; so 

 that the base of an old specimen is five, six and sometimes 

 eight or nine limes larger than young ones. From 



