Hirudinea.] SUBANTARCTIC ISLANDS OF NEW ZEALAND. 373 



External Anatomy. 



The body, apart from the two terminal suckers, is distinguishable into two 

 well-marked regions — neck and trunk. The anterior or buccal sucker is subcircular, 

 or perhaps rather longer than wide, cup-shaped, and attached excentrically to the 

 neck, from which it is separated by a constriction. It is marked by grooves into 

 12 annuli, in addition to the prostomial lobe. There is a pair of eyes on the 9th 

 annulus ; each is a crescent of black pigment, open posteriorly. 



The neck is cylindrical, about one-fourth of the total length of the animal. Its 

 hinder third is very evidently modified as a clitellum ; here the annuli are less dis- 

 tinct, the diameter is rather greater, the ground-colour is lighter and without spots. 



The trunk (or abdomen) is subcylindrical, rather wider than its height, with 

 rounded sides. 



It is absolutely without any trace of gills. My note, written at the time of 

 capture, reads, " I see no gills " ; and after a careful examination of the preserved 

 specimens I cannot detect the slightest sign of any being retracted. There is no 

 interruption of the surface of the body, so far as superficial observation allows me 

 to judge ; at the same time, I should state that I have not yet cut sections, which 

 alone would be absolutely decisive. 



The posterior sucker is circular, not much broader than the body shortly in 

 front of it. There are no " eye-like " marks on it. It is uncoloured. 



Colour. — I noted that the leech, in life, is " red-brown, with paired oval black 

 spots at intervals." As preserved in formol, the tint is paler, and the spots are 

 deep reddish-brown, instead of black. Of the three specimens, one is without spots ; 

 in the other two they are not quite regular in their distribution, but a comparison 

 of these two enables one to recognise two rows on each side — a dorso-lateral, and a 

 ventro-lateral just below the lateral margin of the body ; the latter are less numerous 

 and less regularly arranged. On the trunk the dorso-lateral spots occur on every 

 third annulus, except at the hinder end. 



The dorsal face of the buccal sucker presents a diffused pigment, and in one 

 individual there are also two spots of darker brown on each side near the hinder 

 border ; these are quite distinct from the eyes. 



The clitellum is devoid of spots in all three specimens. 



Annidation. — The arrangement of these spots on the trunk indicates that the 

 segments are trimerous ; but on the neck the spots do not commence till near the 

 clitellum. In one individual, which is a good deal contracted, there are 18 annuli 

 in the neck ; in an extended specimen the limits of these annuli are so indistinct 

 that it is difficult to count them accurately, but a comparison of the three speci- 

 mens gives the following as the constitution of the body :- 



There are 18 annuli in the neck, of which 5 form the clitellum. Each of these 

 latter is apparently biannulate, or even triannulate, in a contracted specimen, so 

 that at first one might suppose that the " annuli " are segments ; but the position 

 of the genital pores negatives this suppositon. 



Paired spots occur on the following annuli : 7, 10, 13, 19, 22, 25, and on every 

 subsequent third annulus up to the 52nd ; then on 54 and 56, beyond which there 

 are three annuli, and an imperfect fourth, without spots. Thus the body, without 

 the suckers, consists of 60 annuli. 



