LOXOSOMA. 355 



manner tliat it is impossible to tell what has been observed and 

 what has been imagined." 



" I have worked/' the Author adds, " upon sections hardened 

 in alcohol or chromic acid ; I have employed the different 

 reagents in vogue, such as osmic acid, and I have not neglected 

 the methods of staining so much practised now-a-days by histo- 

 logists. But I must confess that all these methods of investiga- 

 tion have taught me nothing that I could not see in the living 

 animal. If certain details were rendered more distinct, as, for 

 example, the cells in the stem, which are coloured by the picro- 

 carminate of ammonia, while the gelatinous substance filling it 

 remains uncoloured, the tissues in general became so opaque 

 under the treatment, that I no longer succeeded in reading their 

 structure. I have, therefore, abandoned these methods, which 

 demand much time and care, and in the present case could give 

 me no positive information upon points which direct observation 

 of the living organism had failed to solve." 



The Body and the Skin. 



The body of the Loxosoma^ apart from the stem to which it is 

 attached, may be divided into two parts : the tentacular apjjaratus 

 and the hod^ proper. 



The former consists of a hood (a), and a variable number of 

 tentacles attached to it, and is formed by a direct continuation 

 of the skin surrounding the rest of the body (b), within which 

 are lodged the digestive and reproductive systems. The space 

 enclosed by the hood {capuchon) is called the vestibule (c), and 

 into this the mouth, the generative organs, and the anus, open 

 directly. 



General cavity of the body there is none. There is no empty 

 space amongst the organs ; the gaps between the latter and the 

 skin are occupied by hypodermic cells, out of which the gene- 

 rative organs are formed. 



The form of the animal viewed in front may be compared to 

 that of a pear reversed, the stem being attached to the enlarged 

 extremity (PL XXII, figs. 2, 3, 4). But this pear-shaped body 

 is flattened, or even concave on one side and convex on the 

 other (PI. XXII, figs. 1 and 5). On the concave side, and 

 almost in the middle of the hollow, is a circular, dilatable 

 opening, through which the tentacles are put forth.^ 



Throughout the paper the concave side with the opening is 

 designated the ventral aspect, while tlie side which is convex and 

 entire will be the dorsal aspect; the extremity to which the 



1 This peculiarity in the position of the tentacular crown, placed as it is 

 on one of the sides of the body, instead of at its summit, has suggested the 

 generic name, 



VOL. XVIT. NEW SER. A A 



