106 ESSAY ON CLASSIFICATION. 



in the mode of their development, not only in the differ- 

 ent orders of the class, but even in different genera of the 

 same family. The larvae of many have a close resem- 

 blance to diminutive Ctenophorse, and may be hornolo- 

 gized with this type of Acalephs. 



As I shall frequently refer hereafter to the leading 

 divisions of the animal kingdom, I ought to state here, 

 that I do not adopt some of the changes which have been 

 proposed lately in the limitation of the classes, and which 

 seem to have been pretty generally received with favour. 

 The undivided type of Eadiata appears to me as one of 

 the most natural branches of the animal kingdom, and I 

 consider its subdivision into Coelenterata and Echinoder- 

 mata as an exaggeration of the anatomical differences ob- 

 served between them. 1 As far as the plan of their struc- 

 ture is concerned, they do not differ at all, and that 

 structure is throughout homological. In this branch I 



Ueber den Canal in den Eiern der Ueber die Larve der Comatula, Miil- 



Holothurien, Mullet's Arch., 1854, p. ler's Arch., 1849, p. 400. KROIIN, 



60. Fortsetzung der Beobachtun- (A.,) Ueber die Entwickelung der 



gen uber die Metamorphose der Echi- Seesterne und Holothurien, Muller's 



nodermen, Muller's Arch., 1855, p. Arch., 1853, p. 317. Ueber die Ent- 



67. French abstracts of these papers wickelung einer lebendig gebiihren- 



may be found in Ann. Sc. Nat., 3e den Ophiure, Muller's Arch., 1851, p. 



ser., 1852 and '53, vols. 17, 19, and 338. Ueber die Larve des Echinus 



20, and 4e ser., 1854, vol. 1, by C. brevispinosus, Muller's Arch., 1853, 



DARESTE. An English account is p. 361. Beobachtungen liber Echi- 



published by HUXLEY, (Tn. H.,) Re- nodermenlarven, Muller's Arch., 1854, 



port upon the Researches of Prof, p.208. Ueber einenneuenEntwickel- 



Muller into the Anatomy and Deve- ungsmodus der Ophiuren, Muller's 



lopment of the Echinoderrns, Ann. Arch., 1857, p.369. SCHULTZE,(M.), 



and Mag. Nat. Hist. 2d ser., vol. 8, Ueber die Entwickelung von Ophio- 



1851, p. 1. KOREN und DANIELSSEN lepis squamata, Muller's Arch., 1852, 



in Nyt Magazin for Naturvid, vol. 5, p. 37. GOSSE (R. H.), Tenby, a sea- 



p. 253, Christiania, 1847 ; Ann. Sc. side holiday ; London, 1856, 8vo. 



Nat., p. 347. See also Fauna littoralis l I am surprised to find that J. 



Norvegise, 2d. livr. AGASSIZ, (L.,) Miiller favours the view of a close 



Twelve Lectures, etc., p. 13. DER- affinity between Polyps and Aca- 



BES, (A.,) Sur la formation de 1'em- lephs, and still more that he is in- 



bryon chez 1'oursin comestible, Ann. cliued to refer the Bryozoa to the 



Sc. Nat., 3e ser., vol. 8, p. 80. BUSH, type of Radiata, Muller's Arch., 1858, 



(W.,) Beobachtuugeu, etc., q. a. 8vo., p. 105. 



