PLATE CL. 



Fig. 1. Sylon chcdlengeri, part of a transverse section, passing through the ovary, e, 

 and the " Eikittdruse," A ; a, connective tissue of the mantle ; b, epithelium 

 surrounding the visceral mass ; c, ramified tubes of the gland ; d, female 

 genital pore. Magnified 136 diameters. 



„ 2. Part of the mantle and visceral mass of Sylon schneideri; a, connective tissue 

 of the mantle ; b, epithelium surrounding the visceral mass ; e, ovary ; f, 

 chitinous outer wall of the mantle ; g, thickening of the chitinous outer wall 

 at the place where later on the openings of the mantle-cavity occur ; h, 

 epithelium of the outer side of the mantle ; i, epithelium at the inner side 

 of the mantle ; /, blood-plasma (?) ; n, nervous system. Magnified 136 

 diameters. 



,, 3. Part of the visceral mass of Sylon schneideri ; b and e as in fig. 2 ; c, connective 

 tissue; I, blood-plasma (?). Magnified 136 diameters. 



,, 4. Section through a part of Hippolyte pusiola, with Sylon schneideri attached 

 to it ; e, ovary of the parasite ; n, nervous system of the Hippolyte ; B, 

 basil ary membrane ; r, roots of the Sylon ; m, abdominal flexor muscles of 

 the host. Magnified 30 diameters. 



,, 5. Section in front of the attachment of Sylon schneideri to Hippolyte pusiola; 

 e, m, n, and r as in fig. 4 ; t, testis. Magnified 30 diameters. 



,, 6. Section of the same Sylon as in the two foregoing figures; e, t, as in fig. 5; 

 t', communication of the interior of the testis with the mantle-cavity. 

 Magnified 41 diameters. 



