xcvi NATURAL HISTORY. 



the mantle. It is depressed and tapers towards the extremity ; within the tube, and 

 two hnes distant from the end, there is the small valve, which exists in all the Cepha- 

 lopods that have locomotive organs adapted for propelling them forwards. On either 

 side of the base of the funnel there is an oblong cartilaginous depression, surrounded 

 by a raised margin, to which a corresponding projection on the inner side of the 

 mantle is adapted. This structure for strengthening the attachment between the mantle 

 and the head is met with in all the Decacera, and in Oci/thoe, but does not exist in 

 Octopus, The membranous expansions from the sides of the base of the funnel, cor- 

 responding to the 'cullottes ' in Octopus, extend in Rossia around the anal aperture. 



The rudimentary dorsal shell, or gladius, is not more than nine lines in length, and one 

 line and a half in breadth at its lower and dilated half; there is a longitudinal mesial 

 ridge on its external surface, and a corresponding groove with lateral ridges on the 

 opposite side ; it is of a firm texture, and brown colour anteriorly, but becomes thin, 

 soft, white, and cartilaginous at its posterior extremity. 



The digestive organs of Rossia resemble those of Sepiola, with the exception of the 

 laminated pancreatic caecum being of a simpler form, and the follicles appended to the 

 biliary ducts being more developed ; these are larger, indeed, than in any Cephalopod 

 in which this structure has been found. The horny mandibles, and their surrounding 

 fleshy lips, present no peculiarity worthy of remark. The outer lip, as in Sepiola, is 

 more contracted than in Sepia. The oesophagus descends in the dorsal interspace of 

 the hepatic lobes without dilating to form a crop. The muscular stomach is lined with 

 a cuticle, but is not so strong as in Octopus. The laminated caecum is a simple oval 

 cavity, as in ?^autilus, without spiral appendage. The biliary secretion enters it 

 between two of the widest laminje, which are continued onwards some way into the 

 intestine. The gut ascends without any convolution on the opposite side of the liver, and 

 terminates between the two muscles which connect the base of the funnel with the 

 ventral side of the mantle, and which, from their disposition, serve as a sphincter to 

 the intestine. 



The lower pair of salivary glands are lobulated, arid of the usual proportionate size. The 

 liver is bilobed, each lobe notched at its upper end, and expanding towards the lower 

 end. Besides the proper capsule, which has a smooth glistening surfece, the liver is 

 contained in a strong peritoneal cavity. The two biliary ducts emerge from the lower end 

 and immediately branch out into a mass of larger and simpler follicles, which are arbo- 

 rescent, and extend their ramifications half an inch from the ducts, forming a mass, which 

 conceals the upper halves of both the stomach and rudimentary pancreas. The ink-bag 

 is situated between the liver and the muscles which surround the arms, close to which 

 its duct enters the intestme. The ink is black, of the same tint as the china-ink. 



