188 



Transactions. — Zoology. 



The median dark band varies in width and in density of pig- 

 mentation. In some cases the pigment - spots are so close 

 together as to form a black band ; in other cases they are less 

 close, so that the ground-colour shows between them and in- 

 terrupts the continuity of the band. In some cases the lateral 

 margin of this band extends outwards irregularly at intervals 

 across the neighbouring field of ground-colour, and this may 

 take place to such a degree that the median band coalesces 

 with the intermediate linear streak (c). In one specimen the 

 median band (a) is separable into 3 bands — viz., a pair of ad- 

 median black linear streaks and a median area in which the 

 pigment - spots are less closely aggregated. Naturally, the 

 width of the supramarginal band varies to some degree, 

 though there is always a distinct band of ground-colour be- 

 tween it and the actual margin of the body. 



As to size, it is evident that some of my specimens are quite 

 young and probably immature. The cocoons are empty : 

 perhaps the smallest individuals are but recently hatched. 



Dimensions in Millimetkes. 



Length. 



Breadth. 



Height. 



Sucker. 



One of the individuals (g), which may be the one that bit Mr. 

 Dunlop, is gorged with blood, and is much redder than the 

 rest. It is strongly convex ventrally, and the back is longi- 

 tudinally bent upwards. Its dorsal length (along the curve) 

 is 22 mm., and ventrally (along the curve) 38mm., greatest 

 breadth 11 mm., and height 8 mm. The sucker is only 5 mm. 

 diameter with margins inflated ; it is thus a small indi- 

 vidual. 



I have placed this leech in the genus Hirudo, for it pos- 

 sesses 5 pairs of eyes, on anuuli 1, 2, 3, 5, and 8; and the 

 segmental sensillseon annuli 8, II, 14, 19, and subsequently on 

 every fifth annulus up to the 94th. Tlien we come to abbre- 

 viated segments, and the sensilUe occur on the 97th and 

 99th, but I could not detect any on the 101st annulus. Both 

 the 101st and 102nd are very small, and the anal depression 

 affects them both. 



Of the sensillaj I could detect 8 rows on the dorsal sur- 

 face, but I could not detect any on the ventral. The sensillaB 

 are all situated on the ground-colour, and were very distinct 



