222 Description of the Plates. 



and in the females of all higher Vertebrata; but in the 

 Hirudineae the walls of the generative glands are continuous 

 with the capsules of the generative glands; and, with 

 the exceptions above stated, p. 230, the segmental organs 

 have no opening internally. In the possession of accessory 

 sexual organs, the Hirudineae and Oligochaeta resemble each 

 other, and differ from the other Annelids. 



For the general anatomy of the Leech, see Brandt, Medizinische 

 Zoologie, Bd. ii., pp. 239-253; or Leuckart, Die Mensch- 

 lichen Parasiten, Bd. i., pp. 634-720. 



For the 'segmental organs, see Gratiolet, Ann. Sci. Nat., Ser. iv., 

 tom. xvii., 1862, p. 192, pi. vii., fig. 4. 



For the nervous system, see Leydig, Vergleichende Anatomic, 

 p. 162, ihique citata j and Taf. i., figs. 4 and 6; Taf. ii., figs. 

 '^^^>?>^5y Taf. iii., fig. i ; Taf iv., fig. i ; and for the sensory 

 organs called Ijy him ' Becherformige Sinuesorgane,' see Archiv. 

 fur Anatomic und Physiologic, 1861, p.6oT. For the ' ganglions 

 de renforcement' developed upon the inferior pair of nerves 

 given ofi" by each ganglia of the ventral chain, except the first 

 and the two last, see, in addition to the references given at 

 p. 133 supra, G. R. Treviranus, Zeitschrift fiir Physiologic, 

 Bd. iii., Hft. 2, 1829, pp. 157-J72; cited by Claparede, I. c, 

 P- 35^- 



For the development, see Leuckart, l. c, 686; and Rathke, Bei- 

 trage zur Entwiekelungsgeschichte der Hirudineen (Nephelis, 

 Clepsine), cit. in loco. 



For the existence of blood-corpuscles in the pseudhaemal system, see 

 Quatrefages, Hist. Nat. Annales, \86^, i., p. 63, ii., p. 168, 

 where Si/Uidea armata is stated to possess blood-corpuscles in 

 those vessels ; and the statement as to Gli/cera made in the 

 Ann. Sci. Nat., 1850, iii. 14, p. 288, appears to be withdrawn. 



For a statement as to their presence in the ' pseudhaemal' system 

 of some other Annelids, see Claparede, Ann. and Mag. Nat. 

 Hist., Ser. iii., vol. xx., 1867, p. 350, where Gli/cera is stated 

 to be devoid of the vascular system in question. For the pro- 

 priety, however, of classing Phoronis as an Annelid, as is done 

 at p. 138 sujira, see Allman, Fresh-water Polyzoa, pp. S^Sl, 

 and Dyster, cit., p. 138. 



