358 carl vogt. 



The Stem. 



In the present species this organ is of very simple structure. 

 It is invested by a cuticle of tolerable thickness, especially in old 

 individuals, in which the lower portion of the stem takes on a yellow 

 colour, whilst it at the same time becomes more rigid (PL XXII, 

 fig. 1) . Beneath the cuticle are the hypodermic cells, present- 

 ing the same characters as over the whole of the body, but widely 

 separated, ranged in line and in communication with pale mus- 

 cular fibres, which traverse longitudinally the entire length of the 

 stem, and are distributed over the base of the body. These fibres, 

 which are very delicate and slightly connected, are clearly placed 

 immediately within the cuticle. 



The cells are attached to their inner surface, and are arranged, 

 like beads, along the fibres, which have all the appearance of 

 being excreted from their walls. 



The centre of the stem is occupied by a solid gelatinous sub- 

 stance, transparent as crystal, in which are disposed minute nu- 

 cleated cells of a pale colour^ fusiform or triangular, and from 

 these proceed in all directions most delicate fibrils,which ramify and 

 anastomose, so as to form a complicated network, the ramifications 

 sometimes spreading in one plane, sometimes plunging towards 

 the interior of the stem. This structure is identical with certain 

 connective tissues that are met with in all parts of the animal 

 kingdom. 



A pedal gland, such as has been described by Kowalewsky and 

 Schmidt in other species, is altogether wanting. The lower ex- 

 tremity of the stem is pointed like the nib of a pen, and though 

 it adheres firmly to the epidermis, there is no sign of any 

 special organ of attachment. 



Transverse muscular fibres, antagonistic to the longitudinal 

 fibres, have not been observed. The muscular action must there- 

 fore find its antagonistic force in the elasticity of the cuticle and 

 of the connective tissue filling the stem. The movements of the 

 latter are very energetic, and, besides bending to one side and 

 then straightening itself, which is frequently done, it is occasion- 

 ally contracted into a spiral. 



The Tentacular Apparatus. 



This important portion of the structure is made up of two 

 parts — the liooil (a) and the crown of tentacles (d) . 



The former is an attenuated extension of the skin, and has 

 exactly the shape of the hood of a cloak, which is fastened in 

 front of the person by means of a string. The body- wall, 

 strengthened by a thicker and more rigid cuticle and a more 

 higher developed hypodermic layer upon the dorsal side^ rises 



