2 VERRILL ON THE POLYPS OF THE 



have found it necessary to introduce many changes in the generally received systems of 

 classification, — a result due in part to the investigations of the living coral-polyps by 

 Prof. Agassiz, while in Florida, and partly to my own special studies of this class, while 

 arranging and classifying the unrivalled collection in the Museum of Comparative Zoology. 

 Although many of the results of the observations of Prof. Agassiz have as yet been made 

 public only through his lectures, I have, in every case, endeavored to give the true au- 

 thority for those conclusions that are not original with me. 



In the preparation of this paper, I have been greatly indebted to Prof. Agassiz, who has 

 not only allowed me the unrestricted use of the extensive collection of the museum, but 

 has also, with characteristic liberality, placed in my hands his magnificent series of draw- 

 ings, made from life by Mr. J. Burkhardt. These have beeir of the utmost value, especially 

 in preparing the descriptions of the southern Actinidce, of which I have had no opportunity 

 to examine living specimens. I am also under many obligations to Mr. William Stimpson, 

 who has furnished me with an elegant drawing of Ilalcampa product//, and with valuable notes 

 concerning other species. To Mr. E. S. Morse, my thanks are due for my first opportunity to 

 examine living specimens ofBunodes stella, and for several beautiful drawings of that species 

 and of Edwardsia sipunculoides, some of which are reproduced in the accompanying plate. 



Order I. ALCYONARIA. 



The class of Polyps has undergone many changes, as it has been found necessary, from 

 time to time, to remove groups belonging to other classes, confounded with it so long as 

 their structure was imperfectly understood. The true polyps were for the first time divided 

 into the two natural orders characterized by the number and structure of the tentacles, by 

 Milne-Edwards and Audouin, in 1828, but at that time no special names were applied to 

 the two groups thus established. 



The name Alcyonaria (Alcyoniens) was given to the first of these divisions by Milne- 

 Edwards, 1 in 1834. 



In this order the polyps are more or less cylindrical, made up with eight nearly equal, 

 hollow, elongated spheromeres arranged around the vertical axis and intimately united to 

 each other by their sides, without the interposition of interambulacral spaces. All of them 

 are prolonged at the actinal end into broad tentacles, pinnately lobed along their sides. 



The second order, Zoantharia, has, on the contrary, spheromeres in multiples of six, often 

 very numerous, united so as to leave interambulacral spaces in which the new ones are 

 developed. The tentacles are simple, and generally cylindrical or conical, rarely branching 

 in a furcate manner. 



In the great work of Dana, the Alcyonaria have the same limits, but are considered as 

 a sub-order of the order Actinoidea, — a group which embraces the whole class of Polyps 

 as now restricted, his order Hydroidca having been referred more recently to the class 

 of Acalephs. 



The Alcyonaria have been divided by most modern writers into three natural groups. 



I. Alcyonid.e ; these are tubular and usually much elongated polyps, increasing by 

 lateral or basal gemmation, forming communities by the union of the walls, their bases 

 or appendices, sometimes, also, through the medium of a porous ccenenchyma, and there- 

 fore communicating by irregular pores and cavities. There is no common, specialized, 



1 Eleniens de Zoologie, p. 1046. 1834. 



