Snail-Leeches. 87 



(hence the specific name of sexoculata of some authors), of a 

 triangular form, occupying the fourth, fifth, and sixth seg- 

 ments ; sometimes the first pair are wanting, or the whole six 

 are confused and irregularly placed; colour, variable; body, 

 firm, and semi-crustaceous, rolling up like an oniscus when 

 handled ; posterior sucker large, and sometimes marked with 

 light- coloured rays ; length, from half an inch to nearly an 

 inch (not extended) ; stomachal casca, six pairs, the first five 

 being nearly at right angles to the longitudinal axis of the 

 body, the sixth larger, and directed downwards, but not 

 reaching to the posterior sucker; proboscis dilated towards 

 the base, then again narrowing. 



VAEIETIES. 



A. Body greenish, densely sprinkled with minute dots of 

 a dark colour; back marked with large golden spots, arranged 

 in longitudinal fines, which disappear towards the anterior 

 extremity ; each spot is formed of a number of small granular 

 spots; the body, as seen under the microscope, is marked 

 with faint reddish patches. 



B. Body brown, with very delicate close strias, both lon- 

 gitudinal and transverse. 



0. Body more elongated anteriorly than in the other 

 forms, and softer ; the animal less readily assumes a rolled-up 

 form when handled. Colour a light olive brown, the two- 

 medio-dorsal lines being less distinct than in the other form of 

 the species. Eyes four, five, or six, nearly always confused. 

 Oval sucker, when extended obtusely, triangular; margins of 

 body more sharply crenated than in the other forms. This 

 variety seems to partake both of the characters of G. com- 

 jplanata aud G. bioculata; it is more slug-like than the normal 

 form of the species. The normal form of G. complanata is 

 abundant everywhere, hiding under stones and leaves, and 

 within the stems of aquatic plants. It is prettily marked on 

 the dorsal surface. It deposits its ova, which are sometimes 

 of a delicate pink, on submerged bodies in the months of 

 April and May. 



G. bioculata. Body more attenuated anteriorly than the 

 last species, and considerably smaller; colour light brown, or 

 greenish grey; soft; rings distinct, about sixty-four in number, 

 deeply and sharply serrated at margins ; eyes two in number, 

 black, situated on about the third ring. Back thickly dotted 

 with minute semiconfluent dark spots, more sparingly towards 

 the margins ; a regular row of these spots on each side the 

 axial line of the body, leaving a clear space between the rows. 

 Proboscis distinctly notched at the apex, often protruded to the 

 extent of nearly half its length when the animal is taken out of 



