$$ 207, 208. THE CEPHALOPHORA. 233 
§ 207. 
The nervous system of the Cephalophora is enveloped by a very distinct 
fibrous neurolemma containing often various pigments, which, in some 
‘*pecies, give it, and expecially the ganglia, a weil-marked color. The 
neurolemma enters the ganglia and forms there numerous septa which 
separate the ganglionic globules into groups. These are very distinct, 
and although of variable size, always contain a very large nucleus 
composed of obscure granules in the midst of which are seen usually two 
to four transparent nucleoli of unequal size.” 
These ganglionic globules are very often pedunculated,® and then their 
very slender peduncles or processes usually extend far into the nerves 
which are given off from the ganglion, thus leading one to infer that these 
globules are the origin or termination of the nervous fibres. | Moreover, 
these primitive fibres which traverse the ganglia, are always situated in 
that portion of them which is contiguous to the cesophagus or pharynx, 
while the opposite portion is occupied by the ganglionic globules. 
§ 208. 
There is a great variety in the form and arrangement of the different 
parts of the nervous centre, according to the orders and families, as fol- 
lows.” 
1. The Heteropoda quite resemble the Lamellibranchia by their 
widely-separated ganglia connected by very long commissures, At the 
anterior extremity of their body, and above the oesophagus, there is a 
cerebral mass which sends backwards two long nervous cords, which, after 
passing along each side of the intestinal canal, terminate by entering the 
inferior ganglionic portion (Ganglion pedale), situated near the ventral 
surface. The cerebral portion furnishes nerves to the organs of sense, to 
the skin, and to the lips, while the posterior portion sends them chiefly to 
the foot, and to the muscles of the tail. 
1 These ganglia are orange-colored with Lym- 
maeus, and red with Planorbis, Paludina, Hya- 
ea, Pleurobranchus. 
2 Hannover (Recherch. microscop. sur le Sys- 
.téme nerveux, 1844, p. 69, Pl. VIII.) has very well 
described and figured the ganglion-globules of 
Helix and Limaz. 
8 Judging from KEhrenberg’s figure (Uner- 
kannt. Struktur &c. Tab. VI. fig. I. 12.) of the 
pedunculated ganglion-globules of Arion empiri- 
-corum, he was not aware of the large nuclei which 
they contained. : 
e 2 
* [§ 207, note 4.] Leidy’s results, after very 
careful dissection, do not accord with these, for he 
observed none of the nerve-fibres originate or ter- 
aninate in the ganglionary globules; see loc. cit. 
vol. I. p. 243. — Ep. 
t [ § 208, note 1.] See also Alder and Hancock, 
loc. cit. Part. II. Pl. IL. fig. 9 (Dendronotus), Pl. 
IV. fig. 16 (Doto); Part. III. Pl. VIII. fig. 8 
(Eolis); Part. IV. Pl. V. fig. 1, k. (Scydlaea) ; 
Part V. Pl. II. fig: 18 (Doris), Pi. XLIII. fig. 10 
(Antiopa); then Leydig, Ueber Paludina vivi- 
20* 
4 See Helmholtz, De fabr. Syst. nerv. evert. loc, 
cit. p. 10; Hannover, loc. cit. and Will, in Mil- 
ler’s Arch. 1844, p. 76.* 
1 For the descriptions and figures of the nervous 
system of several Cephalophora, see Cuvier, Mém. 
loc. cit. ; Garner, Trans. of the Linn. Soc. XVII. 
p. 488 ; Rymer Jones, Cyclop. of Anat. p. 392, 
Art. Gasteropoda; Anderson, Ibid. III. p. 605, 
Art. Nervous System ; and Van Beneden, Exer- 
cises zoot. loc. cit.t 
2 See Milne Edwards, Ann. d. Sc. Nat. XVI. 
1842, p, 326, Pl. XI., and Dedle Chiaje, Descriz. II. 
para, &c., loc. cit. p. 152, Taf. XIII. fig. 49, a. 8. 
(Paludina); Blanchard, Ann. d. Sc. Nat. XI. 
1849, p. 78, Pl. IIL. fig. 1, Pl. IV. fig. 1 (Janus) ; 
Middendorff, loc. cit. p. 75, Laf. IX. (Chiton) ; 
Leidy, loc. cit. Pl. I. fig. I. 11-14 (Limaz), Pl. 
IV. fig. V. 15-17 (Vaginulus), Pl. V. fig. I. 32, 33, 
34 (Bulimus), Pl. VI. fig. Il. 25, Pl. VII. fig 
VIII. 20, Pl. IX. fig. IV. 26, 27, Pl. X. fig. IV. 
24, 25, 26 (Helix); Pl. XIII. fig. IV. (Helicina), 
Pl. XIV. fig. IV. Pl. XVI. (Glandina). — Ep. 
