GENERAL STRUCTURE OF ZOOPHYTES. V7 
From each cup the extremity of a polyp protrudes itself with its 
coronet of slender tentacles. 
The AcrinomEA, which comprise all the common coral-forming 
species together with the tribe of Actinias, include polyps of various 
sizes, from the microscopic point to a diameter of eighteen inches. 
The presence of internal reproductive lamelle, and the fact of their 
ejecting the ovules by the mouth, separate them widely from the 
Hydroidea. The tentacles are in one or more series, or scattered. 
The coralla may be either calcareous or horny; but the calicles, 
when any exist, are always calcareous. 
In the remarks which follow, I shall be brief with the first order, 
as my own observations can contribute little to what is already known. 
Some general account of these animals is required in this place, to 
serve for comparison with the Actinoidea, on which I shall dwell 
more at length. 
