118 



ESSAY ON CLASSIFICATION. 



the Leeches for instance, approximate more to the type of 

 the Trematods. The Sipunculoids are no doubt more 

 closely related to the Anmilata than to the Holothurioids. 1 

 The class of Crustacea, 011 the contrary, may be con- 

 sidered as one of the best known, as far as its zoological 

 characters and embryonic growth are concerned, the only 

 point still questioned being the relationship of the Ko- 

 tifera. 2 In their mode of development the Lernseans, the 

 Entomostraca proper, and the Cirripeds, agree as closely 

 with one another as they differ from the higher Crustacea. 

 This conformity 3 is the more interesting, as the low posi- 



UDEKEM (J.i>'),Nouvelle classification 

 des Annelides Setigenes abranches, 

 Bull. Ac.; Brux. 1855, IT., p. 533. 



1 PETERS (W.), Ueber die Fort- 

 pflanzungsorgane des Sipunculus, 

 Miiller's Archiv, 1850, p. 382. MiiL- 

 LER (M.), Ueber eine den Sipuncu- 

 liden verwandte Wurnilarve, Muller's 

 Archiv, 1850, p. 439. KROHN (A.), 

 Ueber die Larve des /Sipunculus 

 nudus, etc., Muller's Archiv, 1851, 

 p. 368. SCHMARDA (L.), Zur Natur- 

 geschichtederAdria(Z<me^'t> iridis) 

 Denksch. Wien. Akad. ] 852, vol. 4, 

 p. 117,%. 



! EHHENBERG (C. J.), Die Infu- 

 sionsthierchen, etc., q. a. DALRYM- 

 PLE (J.), Description of an Infusory 

 Animalcule allied to the Genus Not- 

 orama, Philos. Trans. 1844, II., p. 

 331. NAEGELI (H.), Beitriige zur 

 Entwickelungsgeschichte der Rader- 

 thiere, Diss. iuaug. Zurich, 1852, 8vo. 

 fig. LEYDIG (Fn.), Ueber den Bau 

 uud die systematische Stellung der 

 Riiderthiere, Zeitsch. f. wiss. Zool. 

 1854, vol. 6, p. 1. Zur Anatomic 

 und Entwickelungsgeschichte derZa- 

 cinularia socicdis, Zeitsch. f. wiss. 

 Zool. 1852, vol. 3, p. 452. Ueber 

 Hydatina Scata, Muller's Arch. 1857, 

 p. 404. COHN (F.), Ueber die Fort- 

 pflanzung der Riiderthiere, Zeitsch. 

 f. wiss. Zool., 1855, vol. 7, p. 431. 

 HUXLEY (Til. H.), Lacinularia soci- 

 alis, Trans. M. Soc., Micr. Jouru. 



1852, p. 12. WILLIAMSON (W. C.), 

 On the Anatomy of Melicerta ringens. 

 Quart. Micr. Journ. 1852, p.'l. 

 BDRMEISTER (H.), Noch eiuige Worte 

 iiber die systematische Stellung der 

 Riiderthiere, Zeit. f. w. Zool. 1856, 

 vol. 8, p. 152. GOSSE (Tn. H.), On 

 the Structure, Functions and Homo- 

 logies of the Manducatory organs in 

 the class Rotifera, Phil. Trans. Roy. 

 Soc. ; London, 1856, II., p. 419. 



3 JURINE (L.), Histoire des Mon- 

 ocles qui se trouvent aux environs 

 de Geneve ; Paris, 1806, 4to. fig. 

 MILNE-EDWARDS (H.), in Cuvier, 

 Regn.An.edit. illustr. q.a. Crustaces; 

 represents young Limulus. ZAD- 

 DACH (E. G.), De Apodis cancrifor- 

 mis Anatomia et Historia evolutionis 

 BonnjB, 1841, 4to. fig. NORDMANN 

 (AL. v.), Microgr. Beitr. q. a. LEY- 

 DIG (FR.), Ueber Argulus foliaceus, 

 ein Beitrag zur Anatomic, Histologie 

 nnd Eutwickelungsgeschichte dieses 

 Thieres, Zeitsch. f. wiss. Zool. 1850, 

 vol. 2, p. 323. Ueber Artemia salina 

 und Drancliipus staqnalis, Zeitsch. f. 

 wiss. Zool. 1851, voL 3, p. 280. VAN- 

 BEXEDEN (P. J.), Recherches sur 

 quelques Crustaces inferieurs Ann. 

 Sc. Nat. 3e ser. 1851, vol. 16, p. 71. 

 Memoire sur le developpement et 

 1'organisation des Nicothoes, Ann. 

 Sc. Nat. 3e ser. 1850, vol. 13, p. 354. 

 GEGEKBAUR (C.), Ueber die Ent- 

 wickclung der Sagitta, Abh. d. na- 



