364 APPENDIX. 
blood round every part of the body ; the two lateral ones are situated 
at the base of the branchiz (gills), and perform the pulmonary cir- 
culation, and send their blood to the ventrical by two branchial veins. 
The central heart in the Decapoda is semicircular, in Sepiade tri- 
lobate ; in Loliginid the lateral hearts have appendages resembling 
the auricles in the higher class of animals; in Sepiadz a concave 
spongy substance adheres to the inferior parts of the lateral hearts. 
The organs of digestion consist of a cecum and long intestine ; 
the latter, together with the duct, conveying the black liquor from 
the gland which secretes it : both terminate at the base of the cloaca 
anteriorly. The cesophagus in Polypus is greatly dilated before en- 
tering into the stomach, and is buried in and protected by a very 
hard substance; im Eledona the dilatation is rather less, and the 
substance which protects it spongy. In Sepiolade and Loliginide, 
the cesophagus is simple; the stomach in Sepiadz is simple and 
slender. 
The organs of generation are situated at the bottom of the sac in 
all the genera that have been examined, and consist in the male of 
vesicule seminales (seminal vessels), terminating in a common aper- 
ture, whose sides are slightly produced into a tube. In the female 
the ovaria (the ovaries) are two, and in most of the genera terminate 
by a common duct; in others by two oviducts. 
The glans atrifera, or the gland which secretes the black liquor 
(named Atramentum by the ancients, and minutely mentioned by 
Pliny), is composed of a spongy substance ; is immersed in the under 
surface of the liver in all the genera of the Order Octopoda ; is 
placed under it in all the genera of the Order Decapoda; and termi- 
nates in a duct varying much in proportional diameter and length in 
the different genera; but in all the genera this duct terminates close 
to the anus at the base of the cloaca. 
Their nervous system is very remarkable: the brain is situated on 
the lateral and anterior parts of that cartilage (through which the 
cesophagus passes to join the stomach), is very irregularly formed, 
and is remarkably small : those masses of cerebral matter formed by 
the junctions of the fibres of the optic nerve, are nearly thrice the size 
of that cerebral mass denominated the bram. The anterior part of 
the heart receives internally some very slender fibres from the region 
of the mouth, and many of these fibres sometimes unite before they 
join the lateral aspects of the brain; but the smaller fibres of the 
nerves, which arise from the different parts of the sac, and from the 
intestines, join the posterior part of the brain. 
Their eggs vary very much in their formand colour in the dif- 
