16 Moll. 
M0LLU8CA. 
5 . Nervous System. 
W. Yignal gives a general description of the anatomical arrangement 
and microscopical structure of the nervous system in the Mollusca , which 
he has studied chiefly in Helix pomatia and hortensis, Limax maximus, 
Avion empiricorum, Paludina vivipara , Limncea stagnalis , Aplysia depi - 
Ians, Pecten maximus and opercularis, A nodonta cygnea , and My a arenaria. 
The ganglion-cells are mostly unipolar ; bi- or multipolar ganglion-cells 
are very rare, especially in the Gastropods. The microscopical structure 
of the sympathie (or, as he terms them, “myenteric”) nerves is entirely 
similar to that of those regulating the animal functions. Arch. Z. exp6r. 
(2) i. pp. 326-342 & 289, pi. xvi. 
Arrangement of the nervous system of the adult Bythinia tentaculata 
described by P. B. Sarasin in his history of development of that species; 
Arb. z. Inst. Wiirzb. vi. pt. 2, pp. 41-43. 
B. Haller describes the nervous system of Fissurella, Haliotis , and 
several Trochidce, especially Turbo rugosus (L.), with several critical re- 
marks on Ihering’s paper [Zool. Rec. xiii. Moll. p. 18]. The transverse 
commissures between the pedal nerves are, according to him, not inherited 
from the Vermes, but acquired in the Molluscan division independently, 
as in the lowest of them, viz., the Chitonidce, they form an irregular net- 
work. Morph. JB. ix. pp. 1-98, 7 pis. Short abstract in J. It. Micr. Soc. 
(2) iii. p. 828 ; a more full abstract in JB. mal. Ges. vi. [1884] 
pp. 301-304. 
H. Wegmann and Lacaze-Duthiers discuss the nerve-strings in the 
foot of Haliotis, and come to the conclusion that the epipodium is a 
dependence of the mantle ; C.R. xcvii. pp. 274-277. 
6 . Organs of Sense. 
The visual organs in Solen described by B. Sharp, P. Ac. Philad. 1883, 
p. 248. 
H. Simroth again discusses the different opinions as to the sense of 
smelling in land snails, and comes to the conclusion that the chemical 
senses, smell and taste, are united and seated in the whole skin, but more 
specialized in the feelers, and especially in the orifice of the pulmonary 
organ ; JB. mal. Ges. x. pp. 23-30. 
The olfactory organ of Spengel discovered also in Nautilus by Lan- 
kester & Bourne, Q. J. Micr. Sci. xxiii. p. 340. 
Sensitive cells found in the base of the tentacles in the Limnceidce , the 
upper feelers of the terrestrial Pulmonata, and the oral cavity of Helix 
and some Limnceidce ; Spengel : s olfactory ganglion found in Helix 
personata, but in no other terrestrial Pulmonate. The former are want- 
ing in all fresh-water Prosobranchiata which the author has had occasion 
to examine. P. B. Sarasin, Arb. z. Inst. Wurzb. vi. pt. 2, pp. 91-108, 
1 pl * 
Cup-shaped sensitive cells in the oral cavity of Fissurella and 
Haliotis ; B. Haller, Morph. JB. ix. In that of Chiton ; id. Arb. 
