486 THE BLOOD-CORPUSCLES OP THE ANNELIDES. 



the plate of figures of this parasite, given in Odier's well-known 

 paper in the ' Memoires Soc. Hist. Natur. Paris/ i. p. 70, 1822, 

 show that its claims to be allowed to remain in the separate 

 family with the animals of much the same unlovely habits and 

 external form as itself are not lightly to be set aside on the score 

 of their being based simply on teleological adaptations, whilst, on 

 the other hand, the memoirs of Henle (Miiller's 'Archiv,' 1835, 

 p. 574) and of Dorner (loc. cit.), dealing as they do with many 

 important points of the internal anatomy only imperfectly handled 

 by the first-named authority, do certainly lend some support to the 

 opposite view of its affinities, — a view which, as already stated, 

 Gegenbaur, in the last edition (1878) of his ■ Grundriss der Yer- 

 gleichenden Anatomie' (p. 134), supports. 



My statements as to the existence of corpusculated blood in the 

 vascular system of Branchiobdella, and as to the communication 

 of that system with its large perivisceral cavity, were based, and 



Edwards, Burmeister, Wiegmann oder R. Leuckart nimmt, und vor allem, ob er die 

 Hirudineen mit ihnen verbinden oder zu den Planarieen (Dendrocoelen, Rhabdocoelen) 

 und Trematoden hinuberfuhren will.' It is true that Leuckart does (' Menschl. 

 Parasit.' i. p. 156) put the Hirudineae together with the other orders, the Turbellarians, 

 Cestodes, aud Trematodes, into a class ' Platodes,' which he keeps separate from a 

 class 'Annelides,' containing the four orders, Acanthocephali, Nematodes, Chaeto- 

 gnathi, and Chaetopodes. He appears to me, however, to have done this rather for 

 purposes of convenience as a helminthologist than as a zoologist ; at any rate in the 

 'Lehrbuch der Zootomie,' published in 1847 by himself and Professor Heinrich Frey, 

 the Hirudineae, s. Abranchiati, are ranged as a sub-order under a sub-class ' Annelides,' 

 and in the ' Menschlichen Parasiten' (p. 673) itself, we find this excellent authority, 

 after specifying the points of similarity which subsist between the leeches and Trema- 

 todes as regards their reproductive system, saying : — ' Die Aehnlichkeit mit den 

 Trematoden, die wir so eben hervorhoben, erstreckt sich iibrigens keineswegs bis auf 

 die Einzelnheiten der anatomischen Bildung. Es finden sich hierin vielmehr so zahl- 

 reiche und durchgreifende Unterscheide, dass sich der Typus der Hirudineen auch in 

 dieser Hinsicht als ein selbstandiger zu erkennen giebt.' Claus, in the last edition 

 (1876) of his 'Grundzuge der Zoologie,' having in view, I apprehend, not only the 

 utterances of Professor Leuckart, but also the discussions which had taken place 

 between Claparede and De Quatrefages (' Bibliotheque Universelle de Geneve,' N.S. 

 vol. xxii. 1865 ; 'Bull. Sci.' p. 346 ; and ' Annales des Sciences Naturelles') upon this 

 subject, writes as follows (p. 395): — 'Man hat daher neuerdings zumal im Hinblick 

 auf die nahe Verwandtschaft mancher Discophoren und Polystomeen die Anneliden als 

 systematische Einheit ganz aufgegeben und die Auflbsung derselben in gegliederte 

 Plattwurmer und gegliederte Pvundwurmer befurwortet, allein einerseits erscheint der 

 Anschluss an jene niedere Wurmclasse keineswegs auf die gesammte Organisation 

 durchgreifend, andererseits gerade in dem gemeinsamen Charakter der Segmentirung 

 ein so wesentliches die hohere Lebensstufe bedingendes Merkmal gegeben, dass wir 

 den Verband der Anneliden als wohl gegriindet betrachten.' 



