Rev. W. Houghton on the Snail-Leech. 249 



species, but have never found G. mar(jinata except on these 

 two occasions; indeed, in this very Barston Brook, I have turned 

 over hundreds of stones, and not far from the spot where I had 

 first seen them, but without success. The drawings which ac- 

 company this notice were done for me by my kind friend I\Irs. 

 Rumsey, of Solihull ; the specimen, of which the illustration is 

 a very faithful likeness, is still living in a glass vessel in my 

 room. I refrain from making further remarks on this leech at 

 present, as I hope by-and-by to offer some observations on 

 this family, with a monograph of all the British species which 

 form the famdy Glossiphonid^. 



Glossiphonia marginata. Plate XVI. C. ligs. 1 & 2. 

 Body, when at rest, nearly elliptical, but narrowing towards 

 the anterior extremity; capable of great elongation, when it 

 assumes a linear form. Back, when arched, showing the rings 

 very clearly; marked longitudinally with five regular rows 

 of hght-yellow dots, equidistant, and thinly sprinkled with 

 smaller dots of the same colour, the central row alone extending 

 nearly the whole length of the animal. Margins light-coloured 

 and transparent, having at intervals two narrow dark-coloured 

 parallel lines, which are at right angles to the axis of the 

 body. Ground-colour of body claret. Oral sucker constricted 

 at the base, subtriangular or lozenge-shaped, forming a well- 

 defined head. Extremity on the upper surface almost trans- 

 parent. Head with a light-claret-coloured patch on either side, 

 giving It, if examined without the aid of a lens, a truncate 

 appearance. Eyes four, arranged in two longitudinal series, 

 convergmg anteriorly; the posterior pair much the largest! 

 Posterior sucker very large, round, with about twelve distinct 

 claret-coloured rings. Stomachal caeca seven pairs, with three 

 smaller ones in front, the former bifurcate and nearly at ric>-ht 

 angles to the longitudinal axis of the body; the seventh pair 

 immediately bending downwards and extending to the base of 

 the posterior sucker. Colour of the caca a deep green. 



Length when at rest, about 6'". Ditto, when extended 1" 

 Breadth when at rest, 2'". ' 



Habitat. Bala Lake. Brook near Solihull, Warwickshire. 

 I remain, Gentlemen, Yours, &c., 



W. Houghton. 



EXPLANATION OF PLATE XVL C. 



Fig. \. Glossiphonia martjinata e.vtcnded (magnified] 

 Fig. 2. Ditto, natural size. 



Ann. ^-Maff.N. Hist. Svv.'.i. Vol.\. 17 



