16 
THE VOYAGE OF H.M.S. CHALLENGER. 
These are the only connective cords visible externally, the others (cerebro-pedal : 
cpc .; cerebro-plenral: cchc .; pleuro-pedal :pchc.) being hidden under the cellular coating 
of the centres. It is true, however, that the shrunken part binding together the 
brachial and pedal ganglia, which are far apart from one another, may be called the 
brachio-pedal connective cord, as in the (Egopsids. But these brachial centres 
(innervating the arms by their anterior part) and pedal centres (innervating the funnel 
by their postero-ventral part) only constitute a single pair of ganglia as has been already 
proved by the development. 1 
In the pleuro-visceral centres should be distinguished:— 
A. The pleural (lateral), from which arise the pallia! nerves ( pl.n .) ; 2 and 
B. The true visceral ganglia, from which arise the visceral nerves (PI. III. and 
PI. V., v.n.). 
iv 
Fig. M. — Pedo-brachial connective of Ommatostrephes pteropus; left-hand side view, magnified, i, brachial nerves; ii, 
part of a brachial nerve coming from the pedal ganglion ; iii, pedal ganglion ; iv, brachial ganglion. 
These latter nerves, which arise separately (PI. V. fig. 2, v.n.), could not be followed in 
Spirula peronii. In Spirilla reticulata it has been shown that they are closely united 
(Fig. S, xi) to the back of the anus, in the same manner as in the (Egopsids, and not 
by a long “commissure” as in Sepia. They do not, however, at their point of 
junction form a true ganglion, as in the first mentioned. From this junction arise 
1 In Ommatostrephes pteropus and lllex coindeti, examined for comparison with Spirula , are found, at the 
surface of the pedo-brachial connective, ten nervous bundles coming from the pedal centres properly so-called, 
and going each to be joined to one of the brachial nerves (Eig. M). There is then no need of histological 
researches (like those of Owsjannikow and Kowalevski, Ueber das central nervensystem und das Gehororgan 
der Cephalopoden, Mem. Acad. d. Sci. St Petersbourg, ser. 7, t. xi., 1867 ; and of Jatta, La innervazione delle 
bracchia dei Cefalopodi, Boll. Soc. Natur. Napoli, anno 3, 1889) to show that the pedal ganglion (or of the 
funnel) contributes to innervate the arms. A similar disposition has already been observed in other (Egopsids 
by Hancock (On the nervous system of Ommastrephes todarus, Ann. Mag. Nat. Hist., ser. 2, vol. x., 1852, p. 2), 
Posselt (Todarodes sagittatus [Lamk.] Stp., Vidensh. Meddel. naturh. Foren., 1890, p. 238), and Appellof 
(Teuthologische Beitrage, ii., Bergens Museums Aarsberetning, 1890, p. 8). 
2 In the paper : Pelseneer, Sur la valeur morphologique des bras et la composition du systeme nerveux 
central des Cephalopodes (Arch, de Biol., t. viii., 1888), the ganglionic swellings from which arise the pallial 
nerves have been interpreted as anterior visceral (p. 752), and the value of pleural centres was refused to 
them (p. 749). A re-examination has made evident that all the visceral ganglionic elements form a single 
median mass and that the pleural centres are indeed those from which arise the pallial nerves. 
