Benham. — On Acanthodrilus uliginosus. 123 



o* 



however, Captain Hutton has been good enough to send me 

 the type specimen from Christchurch, with the note that " it 

 was collected many years ago in the swamp on which the 

 town of Caversham now stands." The specimen, when it 

 came into my hands, was fairly well preserved, but naturally 

 had lost all colour. It measures 6 in. by fin., and consists of 

 145 segments. In other respects — and allowing, of course, 

 for misinterpretation of the terms "male genital openings" 

 and "vulvae" — the worm agrees with Hutton's description 2). 

 A careful examination of its external characters and of its- 

 internal anatomy enables me to state that it is identical 

 with the worm to which Beddard(3) in 1885 gave the name 

 Acanthodrilus novce-zealandice, a name which henceforth will 

 have to disappear from literature. 



A few years ago the genus to which most of our en- 

 demic earthworms belong was called "Acanthodrilus," but 

 as the number of species has increased, and as these have 

 been submitted to more and more careful scrutiny, it has 

 been deemed necessary to subdivide the genus. Thus, Bed- 

 dard(4) established the genus OctochcBhis in 1892 for a group 

 of species presenting an assemblage of characters differing 

 from the bulk of our species. The pale or white woi*ms, 

 some of considerable size, of sluggish habits, and secreting 

 an abundance of slimy fluid belong here ; they are provided 

 with eight separated ohaetae in each segment, and diffuse 

 nephridia.* But in 1899 Michaelsen(5), the foremost German 

 authority on the group, as a result of the examination of 

 material collected by Schauinsland, suggested further sub- 

 divisions of the typical Acanthodrilid type, thus : Maoridrilus 

 for those species presenting the very peculiar alternation of 

 the nephridiopores, which is practically limited to our New 

 Zealand species ; while the rest of the common species he 

 referred to Notiodrilus, in which the pores form a single 

 series on each side. 



I confess that there is a certain amount of convenience 

 in the subdivision of the genus, but there is no constant cha- 

 racter that accompanies this condition of the nephridiopores ; 

 nor, indeed, is there any very strict regularity in the alter- 

 nation in an individual, and when a series is studied it 

 becomes evident that a good deal of variation occurs. 



The term " Maoridrilus " may, perhaps, be conveniently 

 used as a subgenus, for it is, anyhow, a remarkable fact that 

 this "alternation" of the pores seems limited to New Zea- 

 land species, and occurs also in the genera Plagiochata 

 and Neodnlus, both confined to these Islands — though it also 



* At another time I will present a complete diagnosis of our native 

 species, but at the present I will leave this matter. 



