362 Royal Society. 



which affords confirmation of his opinion that the pigmentary coat- 

 ing is subjacent to the retina. He finds no vestige of a lens, and in 

 place of vitreous humour, a mere viscous matter protecting the 

 retina from the sea-water. 



The organ of hearing, which had escaped detection in the speci- 

 men of iV. Pompilius dissected by Professor Owen, altered as it 

 doubtless had been by long immersion in spirit, was discovered in 

 the example of A'^. umbilicatus examined by the author. It consists 

 of two spheroidal acoustic capsules placed, one on each side, at the 

 union of the supra- and suboesophageal ganglia, and measuring about 

 one-twelfth of an inch in diameter. Each capsule rests internally 

 against the nervous mass, and is received on its outer side into a 

 little depression in the cephalic cartilage. It is enveloped in a kind 

 of fibrous tissue and filled with a cretaceous pulp consisting of mi- 

 nute, elliptical, otoconial particles, presenting under a high power a 

 bright point near each end, varying much in size, and sometimes 

 combined into stellate, cruciform or other figures. Cilia were not 

 observed within the capsules. 



The inside of the mouth is furnished with three groups of papillae, 

 one of which occupies the median line between the orifice of the 

 tongue-sac and commencement of the oesophagus. These lingual 

 papillae, as well as the rest, are clothed with long and slender 

 columnar epithelium-particles. 



The author agrees with Mayer in regarding the well-known folli- 

 cular appendages of the afferent branchial vessels of the Cephalo- 

 poda, as performing the function of kidneys, but admits that they 

 may also serve, by altering their capacity, to regulate the amount of 

 blood passing through the branchiae under changes of pressure to 

 which the animal may be subjected at different depths. These fol- 

 licles are subcylindrical in form, and somewhat dilated at the free 

 extremity, to which is appended a folded and funnel-shaped process 

 of membrane which expands rather suddenly and presents a jagged 

 border. They open by an oval or slit-like orifice into the afferent 

 branchial vessels, on each of which, as Professor Owen has observed, 

 they are disposed in three clusters. The outer membrane is smooth 

 and glossy, homogeneous in structure, and sprinkled over with mi- 

 nute, rounded, transparent bodies, resembling the nuclei of cells. 

 Beneath this layer, flat bundles of fibres, apparently muscular, are 

 traceable here and there, principally disposed in a longitudinal direc- 

 tion, and sometimes branched. The lining membrane consists of a 

 loose epithelial pavement, similar in many respects to that of the 

 uriniferous tubules of the higher animals, the cells containing, be- 

 sides the nuclei, numerous minute oil-globules, or a substance much 

 resembling concrete fatty matter. This membrane is thrown up 

 into very numerous papillae and corrugations, so as greatly to in- 

 crease the extent of surface. The papillae are more numerous to- 

 wards the attached end, and a circlet of longitudinal folds, with 

 transverse zigzag corrugations, radiate from the bottom of the fol- 

 licle, in which a number of small pits or fenestrations are sometimes 

 visible. The funnel-shaped membranous process above noticed is 



