158 —C«; THE ANNELIDES. ; $ 148. 
ring, and others with the cerebral ganglion by means of other small gan- 
lia near the cephalic extremity.” 
With the different orders and sub-orders of the Annelides, the nervous 
system has the following modifications : 
1. The Nemertini differ remarkably from the other Annelides in this 
respect; for their ventral cord is without ganglionic enlargements, and 
composed of two separated cords, one on each side of the body, which 
send off, right and left, lateral branches along their course. These two 
cords arise at the anterior extremity in two ganglia blended together above 
the esophagus, which represent the cerebral ganglion, and send off many 
nervous branches in front. 
2. With the Hirudinei, the ventral ganglia are much fewer than the 
segments of the body, and are bound together by two contiguous cords. 
The first and last of these ganglia are remarkable for their size. The first 
sends filaments to the lips, the second to the caudal sucker. 
The Splanchnic system is composed of a small ganglion situated in front of 
the cerebral one, and with which it is connected by two filaments. By its 
side are two others, which are also small and-connect with the cerebral by 
delicate threads. All three send branches to the oral parts, while a deli- 
cate filament goes to the inferior surface of the intestinal canal, and repre- 
sents an inner splanchnic nerve. 
3. The ventral medulla of the Lumbricini consists of two nervous cords 
1 Brandt, Bemerkungen tiber die Mundmagen- 
oder Eingeweide-nerven der Evertebraten: Leipzig 
1835, p. 37. 
2 Rathké (Danzig. Schrift. loc. cit. p. 100, Taf. 
VI. fig. 10, 11) has thus described the nervous 
system ef Borlasia striata. 
He has seen particularly two pairs of cephalic 
merves arise from the cerebral ganglion. One and 
ithe larger of these is principally distributed to the 
wespiratory fossae of the head, while the other, the 
‘smaller, passes directly in front, probably for the 
‘vermiform organ upon the cephalic extremity. 
Orsted (Beschreib. d. Plattwiirmer loc. cit. p. 5, 
18), appears to be wrong in suspecting that Rathké 
ihas taken the vascular for the nervous system, for 
Quatrefages (Icon. du Régne anim. de Cuvier. 
Zoophytes, Pl. XXXIV. fig. 1) has figured by the 
side of the vascular system, the nervous system of 
Nemertes Camillae, exactly as it is described by 
Rathke. 
* 1§ 148, note 3.] Leydig (le. cit. p. 129) has 
found the structure of the cerebral nervous centre 
of Piscicola, quite different from that as described 
‘by Leo. The cerebral mass is composed of cap- 
sules containing ganglionic globules; these cap- 
sules are symmetrically situated on each side of 
tthe median line, but are connected by a well- 
marked transverse commissure composed of nerve- 
fibres; see Taf. X. 67, 68, 69. See also upon the 
mervous system of the Leeches, Bruch (Ueber 
das Nervensystem des Blutegels : Kin Beitrag zur 
ttopographischen Histiologie des Nervensystems, 
in Siebold and Kolliker’s Zeitsch. 1849, p. 164). 
‘This memeir is principally histological, and bears 
aipon that disputed point, — the alleged direct con 
mection between the ganglion-corpuscles and the 
merve-fibres. It has, however, some topographical 
anatomical details, and the accompanying figures 
would rake the whole subject very clear. — En. 
8 See Brandt ‘and Ratzeburg, Med. Zool. II. p. 
250, Tab. XX1X. B. (Sanguisuga medicinalis), 
and Leo, in Miller’s Arch. 1835, p. 422, Taf. XI. 
fig. 10 (Piscicola geometra). Wagner has found 
an arrangement quite different from the above, in 
Pontobdella muricata (Isis, 1834, p. 181, 
Taf. I. fig. 3). He saw here the ventral gan- 
glia united by a single cord which sends off 
from each side only a single nerve. This nerve, 
after a short course, has a ganglion, and then 
divides into lateral branches. According to Stan- 
nius, these lateral branches are not united together 
by longitudinal cords as is the case with the Am- 
phinome.* 
4 See Brandt, Med. Zool. II. p. 251, Tab. XXIX. 
B. fig. 7, and, Bemerk. tiber die Mundmagennerven 
loc. cit. p. 89 (Sanguisuga medicinalis).t 
+[§ 148, note 4.) See, for some further remarks 
on the Splanchnic system of the Hirudinei and 
Lumbricini, Quatrefages, Ann. d. Sc. Nat. VIL. 
1847, p. 36. According to him that of the Hiru- 
dinei resembles that of the Insects, and is com- 
posed of a chain of ganglia from which pass off 
filaments, some to the abdominal chain, others to 
the jaws, and others still to the walls of the cesoph- 
agus. There is also a frontal ganglionic chain 
which forms in front a real arcade, and from which 
filaments are given off anteriorly. 
With the Lumbricini it is considerably different, 
and he thinks unlike that which has yet been 
described of all the other Annelides. 
See further, Ann. d. Sc. Nat. XIV. 1850, p. 282. 
and XVIII. 1852, p. 167. 
See also Leydig, Siebold and Kélliker’s Zeitsch. 
TIL Hft. 3, p. 315, and Quatrefages, Ann. d. Se 
Nat. XVIII. 1852, p. 816 (Branchellion). — Ep. 
