496 Mr. Garnek on the N^ervous Si/stem of Molluscous Animals. 



the long cartilages mentioned above are not such, instead of spinal car- 

 tilages. 



The brain of the Sepia (Tab. XXVII. fig. 2 & 3.) consists of several parts or 

 ganglia conjoined into a ring around the oesophagus, (from which it is only 

 separated by a sort of dura mater,) and enveloped by the large cerebral carti- 

 lage. Superiorly, upon the oesophagus, we find the ring expanded into a lobe 

 (fig. 2 & 3, A.), cordate in shape, and giving in front four nerves (a.) to the 

 labial ganglia (E.), and two bands (b.) descending to the anterior part (B.) of 

 the lower division of the brain. The optic nerves (c.) arise from each side of 

 this lobe, and then swell into two large ganglia (F.), which subdivide into 

 numerous filaments, piercing the coats of the eye, and forming the retina. 

 This lobe is also continuous with 1#ie posterior part (C.) of the inferior por- 

 tion of the ring by the broad band (c'.). The anterior part of the inferior 

 portion gives its nerves to the feet, as it does in the Gasteropoda to the undi- 

 vided locomotive foot of those animals. The anterior and posterior parts are 

 connected together, but not quite so intimately as they are in some Gasteropoda. 

 The anterior part, besides the pedal nerves (d.), sends a band (e.) to the labial 

 ganglion, as we saw it did in the Buccinum to the ganglia, which in that animal 

 gave off both tiie labial and pharyngeal liranches. Here the labial and pharyn- 

 geal ganglia (D.) are distinct ; the latter being connected to the former by two 

 nervous bands (fig. 1, 2 & 3,/.), as we saw in Patella. The posterior part of the 

 inferior portion gives off the two branchio-visceral nerves {g.) ; more outwardly 

 the nerves of the mantle (A.), tlte great agent in drawing in the water to the 

 branchiae of the animal ; more outwardly still, nerves (/.) which mount over the 

 superior lobe and supply the retractor muscles : it also, in the Sepia, gives off 

 here the two nerves M'hich supply the respiratory valves. The nerves going to 

 the mantle are distinct from those which supply the siphon or funnel (_/.), nuchal 

 valve (A-.), &c. There are three nerves for the siphon, and two for the lateral 

 valves. The aorta separates the part affording the branchio-visceral nerves, &c. 

 from the more anterior half of this part, giving siphonic nerves*. 



* 'ITie siphon is the expellent tube giving exit to the disaerated water, to the ink, fseces, and se- 

 cretions. In respiration the Cephalopoda, with an inhaurient sac, and a valve in their siphon or 

 funnel to prevent the entry of the water by the wrong opening, and also valves at the sides of the 

 neck, and base of tlie siphon, to hinder its escape by the wide opening for its entry ; ha^ng likewise pro- 

 tuberances on the inner surface of the sac, exactly fitting acetabula at the base of the siphon, for the 



