Benham. — New Species of Leech (Hirudo antipodum). 191 



the same species, and even in the different jaws of the same 

 individual, this distinction hardly deserves generic rank." On 

 the next page (367) he considers this question a little more 

 fully, and proceeds, " So long as the denticles are sufficiently 

 numerous and well formed to enable the leech to live by 

 sucking blood it is plain that the reduction has not reached a 

 point at which the formation of a new genus becomes impera- 

 tive." It is true that much systematic work has been done 

 since Whitman's paper was published, but as I have not 

 access to E. Blanchard's papers (except that dealing with the 

 Italian leeches, in the Boll. Mus., Zool. Torino, ix., No. 192), 

 and as my species does not fit into any of the genera (other 

 than Hirudo) enumerated in Perrier's " Zoologie," I prefer, 

 as I have said, to leave our New Zealand species in the genus 

 Hirudo. 



It may be well to mention that the edentulous leeches of 

 Japan, referred to the genus Whitmannia by E. Blanchard 

 {:= Leptostoma, Whitman), differ in the details of the annu- 

 lation of the body as well as in the position by the genital 

 pores. Moreover, the genus consists of land-leeches. 



The Cocoon. 



The cocoon, of which I give a figure, agrees generally with 

 the account given by Moquin-Tandon* of that of Hirudo 

 medicinalis (p. 177 and pi. xi.). It is regularly ovate, of 

 dark-brown colour and horny texture ; it measures 14 mm. 

 by 8 mm. over all. The outer surface consists of stiff horny 

 filaments projecting outwards from a continuous horny mem- 

 brane. The latter is marked by numerous shallow depres- 

 sions, each irregularly circular, or, more properly, hexagonal or 

 polygonal, in outline. The low walls which separate the de- 

 pressions give origin, at the point where two or more meet, to 

 short vertical filaments; these branch into two or three shorter 

 threads, lying in a plane at right angles to the vertical fila- 

 ments : these threads terminate in a small thickening, and 

 interlace, or may even be united with neighbouring threads. 

 In this way a very loose and easily broken felt- work is pro- 

 duced. The basement membrane, though tough, is quite thin, 

 and on the inner surface is smooth and shiny, and marked by 

 feebly convex areas corresponding with the shallow pits seen 

 on the outside. I opened one cocoon, which was empty ; and 

 as they both floated in the preserving fluid I judge that the 

 other is also empty. Probably the smaller leeches captured 

 are only recently hatched, but there is no perforation in the 

 wall of the cocoon. 



* Moquin-Tandon, Monogr. d. 1. Fam. des Hirudinees, 1846. 



