Benham. — Tivo Nc:v Species of Leec/i in N.Z . 181 



Order ARHYNCHOBDELLIDA. 

 Fam. HIRUDINID.E. 

 HiRUDO, Liune, 1758. 

 H. antipodum, Benham. 

 H. mauiana, n. sp. 



Placobdella maorica, n. sp. 



A single specimen of this small aquatic leech was forwarded 

 to me by Professor Chilton, who had received it from Mr. T. 

 Horan, of Ruapuke Island, in Foveaux Strait. It was pre- 

 served in alcohol, and was a good deal contracted. 



Shape and Dimensions. — The form is oval, much arched 

 dorsallv, concave ventrally. The head was curved downwards. 

 The posterior end was also bent downwards, so that the hinder 

 sucker was hidden when the animal was viewed from above. 

 The lateral margins were similarly inflexed, rounded (fig. 1). 



The total length measured along the curved dorsum was 

 9 mm. ; the transverse diameter, 4 mm. ; the widest part 

 being about the middle of the body. The posterior sucker 

 measured TTSmm. across, and the margins inflexed. Pro- 

 bably in life the animal would be about an inch in length. 



Colour and External Features. — The colour is a uniform pale- 

 greyish brown in spirit, "without any trace of pattern or coloured 

 spots, but under a dissecting-lens one or more rows of minute 

 brown dots were visible in each annulus. Certain of the an- 

 nuli (see below) carry four papillae, regularly arranged so as to 

 form four longitudinal rows along the dorsal surface. 



As for the " segmental sensillse," on which Whitman (16, 19) 

 laid so great a stress in his valuable work on the land-leeches 

 of Japan, and which have since been utilised for the purpose 

 of plotting out the segments, I was unable to recognise any 

 definite organs. Oka (14) and Castle (8) have also found a 

 difficulty in applying this method to some members of the 

 family Glossosiphonidee. 



There is a single pair of eyes on the 3rd annulus. They are 

 not quite symmetrical, as that on the left side is slightly more 

 anteriorly placed than the right eye. Possibly this ocular 

 annulus is double ; but in the following enumeration of somites 

 and annuli I have refrained from a too detailed analysis, 

 as it is extremely difficult on a preserved and strongly con- 

 tracted specimen, especially when only a single individual is 

 at hand, to be certain of the difference between ann^di and 

 " \vrinklings," even in longitudinal sections. Consequently I 

 neglect the apparently double nature of certain annuli, and 



