340 OBSERVATIONS ON THE CHLORAEMIDAE, 



Studer in his acoount of Brada mammillata* describes the 

 epithelium as consisting of narrow cylindrical cells, and gives an 

 account of certain sac-like structures formed from groups of 

 modified epithelial cells, which he regards as glands, leading by 

 a duct to a pore on the summit of one of the tubercles. These 

 so-called glands are the basal ganglia of the papillae described 

 below. Joyeux-Laffuie holds with Kolliker that there is every 

 reason to regard the papillae as tactile organs. 



In most respects my own observations on this point agree with 

 those of Claparede; and I have been able to add some details 

 regarding the structure of the appendages in question which go 

 to confirm his opinion of their function. In Coppingeria (figs. 

 11-14) all the papillae have essentially the same structure. Most 

 externally is a thick firm layer continuous with the cuticle of the 

 general surface. Immediately below this is a thin layer continuous 

 with the epithelium. These layers bound a cylindrical cavity, which 

 is continued at the base into a narrow canal. Immediately below 

 the base of each papilla is a little ganglion composed of a rounded 

 group of cells with a mass of granular matter on its deeper face.f 

 Delicate strands run outwards from this basal ganglion and, 

 passing through the narrow neck of the papilla, enter a second 

 ganglion in the base of the latter. From this there runs to the 

 extremity of the papilla an axial strand of fibres with occasional 

 nuclei, and from this run out a few similar but finer branch 

 strands, which end in the epithelium. The axial strand breaks 

 up at the end into a few delicate radiating fibres, which terminate 

 in a group of cells, constituting what might be regarded as a third 

 ganglion at the extremity of the papilla. 



In view of their structure, there can be no doubt that these are 

 sensory papillae. They contain no muscular elements, and, there- 

 fore, can have nothing to do with locomotion or fixation. They 

 contain no cells that can be construed as gland-cells, and therefore 



* "Beitrage zur Naturgeschichte wirbelloser Thiere in Kerguelensland. " 

 'Arch, f. Naturg.' 1878. 



t The granular matter is not present in the case of the elongated papillae 

 at the anterior end of the body. 



