8o 



A n a t ( I m i c a 1 Re m ar k s. 



The anatomy of this genus has been studied by Cuvier ^), Eschricht ^), Souleyet ^), 

 Wagner 'j, Pklseneer ^) and Sciialfejekf "). I have thought it better to give a few notes with 

 respect to the central nervous s\-steni about which Pelseneer gave a most detailed description. 

 As I differ from him in a few points, 1 cannot let them pass in silence. I have examined some 

 specimens of Clicme limacina (Leyden Museum). 



The central nervous system of CHone is constituted like that of the Pneumonodermatidae, 

 viz. the form and disposition of the ganglia is nearly (juitc the same. In Clioiw, the pleuro- 

 visceral connective is a little shorter, and the pedal ganglia present a long commissure (which, 

 however, does not always occur). 



I. The cerebral ganglia (PI. V, fig. 144) are situated above the oesophagus, and exhibit a 

 distinct commissure. Three pair of connectives issue from them. 



A. l'"rom the oesophageal surface of each ganglion a thin connective {dc) pa.sses to the 

 buccal ganglia. 



B. P^rom the lateral side a strong connective {pc) goes to the pedal ganglion. 



C. A little more distally, nearly parallel to the foregoing one a cerebro-pleural connective 

 iph-) is discernible. 



The last two connectives are longer than in the Pneumonodermatidae. 



From each cerebral ganglion several nerves arise. 



p^'roni the dorsal [tart two nerves (i, 2) proceed to the nuchal tentacle. They 

 are the oliactory and the optic nerve, both ending in a swelling. The optic nerve (2) 

 exhibits at its base a ganglionic enlargement, readily visible. An attentive examination 

 shows, that it consists of two elongated swellings (fig. 145), each with a large nucleus. 

 This fact seems not to have been ob.served before. I could not discover an anastomcsis 

 between the two nerves, but .such a connection has been mentioned by Boas ^), who studied 

 it in CHone. 



p'rom the lateral side of the cerebral ganglion, a little ventrally, a nerve (fig. 144, 3) 

 passes to the otocyst. 



I have seen two large trunks arising from the iVont part of the cerebral ganglion. 

 The lateral one .soon divides into two branches, each of which sends off a slender nerve 

 to the skin (4, 5). The lateral branch (4) innervates the ventral buccal cone; the median 

 (5) goes to the labial tentacle. The median trunk eijually divides into two nerves (6, 7), 



1) Memoire sur le Clio borealis. Ann. Mus. d'Hist. Natur. vol. 11 (1802), p. 242 — 249. 



2) .^natomische Untersuchungen iiber die Clione borcalis (183SJ. 



3) Voyage de la Bonite, vol. II, p. 275 — 288, pi. XV, figs. I — 17. 



4) Die Wirbellosen des Weissea Meeres. Bd. I (18S5), p. 89 — 120. 



5) Tlie cephalic appendages of the Gymnosomalous Tteropoda, and especially of Clione, Quarterly Joui-n. Micr. Sci. (1885), 

 vol. XXV, p. 491 — 507, pi. XXXV, and Recherches sur le systeme nerveux des Ptcropodes, Arch, de Biol., vol. VII, p. 96 — loi, 

 pi. IV, figs. 1—4. 



6) Zur .Anatomic der Clioiic liiiiacina^ Zool. .\nz., Jahrg. XII, p. iSS — 190. 



7) Spolia atlantica, p. 143. 



