Mr. J. D. Dana on Zoophytes. 107 



These are the principal authors since Lamarck who have un- 

 dertaken a general arrangement of the class of Zoophytes. The 

 " Stony Corals" have quite recently been arranged mostly from 

 the corals alone by Mr. J. E. Gray of London*. We may ex- 

 press the belief, without entering into any criticisms on his clas- 

 sification, that with a more extended study of the animals and 

 their corals, he would not have separated the Milleporce and He- 

 lioporce so widely from the Pocilloporce ; the Stylastridce from 

 the Sideroporce; the Montiporce from a part of Lamarck's Po- 

 ntes; the Fungice from the Pavonice; nor united into a single 

 group the Pavonice and many Astrcece ; nor the Fungice, Fla- 

 bella and Meandrince : — in the last case giving an unreal import- 

 ance to the oblong shape of the Flabella, and implying a relation 

 which is wholly without foundation between the oblong cell of 

 the Meandrince, Flabella and Fungice ; for in the first, the form 

 arises from budding ; in the second, it is the shape of the polyp's 

 disc ; and in the third, the cell is only a depression at the centre 

 of the disc, and the form has not even generic importance. 



Before giving a general view of the classification of Zoophytes, 

 to which the writer has been led by the study of coral animals f, 

 the importance of different characters as a basis of classification 

 may be briefly considered. 



Owing to the simplicity of polyps, there are few organs or 

 functions to afford distinctive characters. They are as follows : 

 I. The digestive system. II. The ovarian. III. The modes of 

 budding and growth. IV. The tentacles and general character 

 of the exterior. V. The secretion of coral and its nature. 



I. The Digestive System. — In this system the stomach varies 

 (1) in length as compared with the internal or visceral cavity 

 below, and (2) in the character of the parts below and around it. 

 In the first particular, the difference is one of less general im- 

 portance than has been allowed; the relative length in the 

 Actinice and most Actinoid corals is between four- fifths and one- 

 third ; in the Zoanthidce it is between one-third and one-sixth ; 

 in the Alcyonaria, between one-third and one-twentieth; in the 

 Hydroidea the stomach is sometimes much shorter in proportion 

 than in many Alcyonaria, though often far longer. In the second 

 particular the difference is wide, the Actinoidea having the sto- 



* "An Outline of an Arrangement of Stony Corals," by J. E. Gray, 

 F.R.S. &c. : Annals and Magazine of Natural History, xix. 120, Feb. 1847. 



t As it may be of some importance to those interested in the department 

 of Zoophytes, the writer here states that the animals of more than sixty 

 species of coral animals, exclusive of Alcyonaria and Hydroidea, and per- 

 taining nearly to every genus, have been figured by him, from living spe- 

 cimens obtained in the Pacific and East Indies, and these figures will appear, 

 along with others of different corals whose animals were not obtained, in the 

 forthcoming Atlas to accompany the Report on Zoophytes. 



8* 



