H'SG FOURTH REPORT — 1834. 



nous, transparent parts, found constantly in a state of union, 

 naturalists seem hardly to be agreed, whether these parts belong 

 to the same animal, or wliether they constitute two distinct in- 

 dividuals, although in form always more or less dissimilar. 

 Blainville embraces the former opinion ; Q.uoy and Gaimard, as 

 well as Cuvier, seem inclined to the latter. It would not be 

 difficult to point out other instances in which we want further 

 information with respect to the Acalepha, The limits of this 

 Report forbid, however, our dwelling any longer upon this class. 

 It is one especially in which every new observation will have its 

 value ; and it is only to be regretted that so few persons have it 

 in their power to study these animals in a recent state, in which 

 alone they admit of such an examination as is likely to conduct 

 to any important discoveries. 



4. Polypi. — It is not advancing too much to affirm that natu- 

 ralists are only just beginning to get an insight into the natural 

 arrangement of that immense assemblage of beings which con- 

 stitutes Cuvier's fourth class of Zoophytes, and that even this in- 

 sight extends but as yet to comparatively few families. Their 

 researches, however, are sufficiently advanced to prove clearly, 

 that the true situation and affinities of these animals are in many 

 cases very different from those which have been assigned to them 

 in the It^gne Animal. Some have been shown to possess a struc- 

 ture entitling them to a higher place in the scale of organization ; 

 while in others the animal powers seem so reduced, the struc- 

 ture at the same time offering such peculiarities, that they appear 

 to constitute a distinct class, far below the generality of other 

 Zoophytes. One great drawback to our better knowledge of 

 these groups has arisen from the circumstance, that until lately, 

 naturalists, with some few exceptions, scarcely paid any attention 

 to the animals of the Incrusted Polyjn*, which constitute so 

 large a portion of them. They looked only to the characters of 

 the calcareous covering ; and it is not surprising that with this 

 lialf-knowledge they should fall into many erroneous notions 

 with respect to affinities, in their attempts to arrange the species 

 systematically. It is this which at the present day detracts 

 somewhat from the value of the works of Lamourouxf, notwith- 

 standing their great merit in other respects, and the powerful in- 

 fluence which they undoubtedly had over the progress of Zoophy- 

 tology at the time when they appeared. He has made us ac-- 



• The Polypes a Polypier of the French, for which we have no adequate 

 expression in our language. 



+ Hisloire des Polypiers Corallines Flexihles, S(c. Caen, 1816, 8vo. And 

 Exposition MHhodiquc des Genres de I'Ordre des Polypiers, Paris, 1821, 4to. 



