313 



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 

 continuous with the lining membrane. The cavity of each follicle, 

 therefore, communicates with the exterior through the centre of this 

 process, and the aperture is thus guarded by a kind of circular valve 

 permitting the escape of secreted matters, but effectually preventing 

 the entrance of fluid from without. 



Some considerations are next offered in support of the view 

 adopted as to the functions of these vascular appendages. 



