Himdinea.^ SUBANTARCTIC ISLANDS OF NEW ZEALAND. 375 



without teeth on the jaws, for which reason they are not likely to feed on the 

 thick-skinned seals. 



The soil in which the leeches live is moist, and saturated with excrementitious 

 matter from the birds' nests, and, as a rookery contains thousands or, may be, 

 hundreds of thousands of birds, it will be evident that the surroundings are not 

 pleasant to the nose. 



It may be that I am not justified in forming a new genus for this leech, but 

 it does not agree with any diagnosis to which I have access. 



Dimensions. — The specimens before me measure from 28 mm. by 9 mm. to 

 95 mm. by 15 ram., but the majority are about 90 mm. by 10 mm. They are 

 much contracted by the preservative, and in life attain a length of 6 in. even 

 when only partially extended. The greatest breadth is near the hinder half of 

 the body. The posterior sucker is of moderate size ; in a 90 mm. specimen it is 

 7 mm. in diameter. 



Colour. — In life the ground-colour is a dark cocoa-brown, with black reticular 

 markings on the dorsal and on the ventral surface. In the preserved state (formol) 

 the tint is naturally paler, and the black has become a sienna brown ; while in alcohol 

 the ground-colour has changed to a buff. 



Along the median dorsal line is a narrow streak deprived of the dark pigment ; 

 otherwise the whole dorsal surface is marked with dark network. In some parts of 

 the back the reticulation is fine, with wide meshes ; in others coarser, with small 

 meshes ; so that the depth of colour varies. The ventral surface is also pigmented 

 in the same manner, but less deeply. 



External Anatomy. 



The eyes are arranged precisely as in Hirudo. The segments of the body are 

 pentamerous, with the usual abbreviations at each end. I am unable to detect any 

 segmental sensillae, each annulus bearing numerous small and large papillae, with- 

 out any regularity in arrangement ; but the 17 pairs of nephridiopores occupy 

 the same position as in Hirudo. The 4th and 5th annuli, though distinct dorsally, 

 coalesce at the sides ; the same is the case with the 7th and 8th, so as to form in 

 each case a single annulus on the ventral surface. In fact, the only notable difference 

 from Hirudo, so far as the external features are concerned, is the shifting of the 

 female pore one annulus further back ; the genital pores, being at annuli 30/31 

 and 36/37 respectively, are thus separated by 6 annuli instead of by 5. 



From the male pore there issues a blunt, short, conical penis, quite different 

 from the filamentous cirrus of the common medicinal leech. The clitellum is visible 

 in the largest individual in my collection ; it is paler in colour, and the body is here 

 wider than elsewhere ; it commences at the 25th, and extends to the 35th annulus — 

 i.e., from the 2nd annulus of segment ix to the end of the 2nd annulus of segment xi. 



Internal Anatomy. 



The roof of the buccal sucker is deeply grooved ; the jaws are small and quite 

 toothless. 



The'; gut and nephridia, so far as is to be seen in the dissected specimen, agree 

 with those of Hirudo, but the genital organs present points of difference which are 



