




EXPLANATION OF THE PLATES. 


PLATE 1, CEPHALOPODA. 
Fic. 1.—The anatomy of the Argonaut, 
the respiratory sac or mantle and siphon 
being slit, and the viscera displayed. 
s, siphon: m, the cartilaginous prominences of the 
mantle fitting the acetabula at the base of the 
siphon: e,theear-sac: c,thecrop: +,a bristle 
inserted into a dorsal cavity: g,salivary glands : 
i, the ink-bag: 06, the branchie: s¢, the stom- 
ach: ||, the ccecal stomach: 7, the branchial 
ganglia: h, the branchial hearts: 7 ganglion 
of the stomach: 1, nerves of the siphon: 2, do. 
of the mantle: 8, branchial and visceral nerves : 
4, anus: 5, liver: 6, pillars of the siphon: 
7, bile-ducts: 8, aorta: 9, ovary: 10,10 ovi- 
ducts: H, systemic heart drawn down with the 
left branchial vein cut across. 
Many of these references also apply to 
Fig. 5 of this plate. 
2, remains of Pteropoda from the stomach 
of the Argonaut. 
3, Entozoa infesting the same. 
4, acetabula of the arms 
5, the buccal mass, exposed from behind, 
with the brain and eyes, and the ali- 
mentary canal opened. 
O, optie ganglia: 
1, nerves of the feet: C, brain: 
2, subocular gland with its duct: 3, crystalline 
lens: 7, buccal mass: /, mouth. 
6, side view of the maxille. 
P, pharyngeal ganglia: g, salivary glands. 



7, buccal mass opened from before, with 
the anterior or lower part of the brain, 
its nerves, and the esophagus. 
t, tongue: g, salivary glands. 
8, shews the distribution of the branchial 
vessels, 
9, socket of the tongue and its muscles. 
10, plan of the tongue. 

PLATE 2, CHPHALOPODA AND PTEROPODA. 
Fic. 1.—Sepiola Atlantica with its man- 
tle opened. 
7, ink-bladder and rectum: g. stomach : 
b, branchiz. 
0, ovary : 
ov, oviducts : 
2, the beak of the same. 
3, Loligo media. 
0, ovary: ov, oviduct: 6,branchie: g, laminated 
glands: vr, rectum. 
4, young Sepia from ovum. 
Ss a 
2, ab,shellof do.: c, membrane forming the anterior 
lamina of the shell magnified: d, the anterior 
lamina of the shell seen from before, also magni- 
fied: e, one of the middle lamin with its flat- 
tened tubes arising from the sinuous lines, highly 
magnified: f, a particle of the adult shell. 



