Benham. — On Neiv Zealand Eartliioorms. 157 



than twenty years ago — very little was known of the internal 

 anatomy of the group, or of the characters which serve to 

 differentiate genera from one another. Indeed, up till 1872 

 the only extra-European genera that had received distinctive 

 names — which are still retained — were Pontoscolex and Pcri- 

 chcBta, Schmarda (1861). The anatomy of the latter had been 

 studied by Vaillant (1869). Closely similar to it externally, 

 and often confused therewith, is the genus Megascolex, de- 

 scribed from external features by Templeton in 1844. Several 

 other genera had, however, been named from external cha- 

 racters alone, but most of these are now unrecognisable, and 

 have dropped out of zoological literature. 



Now, Perichceta and its ally Megascolex differ from all 

 other earthworiBS — with the exception of a genus to be men- 

 tioned below, and only defined in 1892— in having very 

 numerous bristles or chaetse, and in having them arranged in 

 a circle round each segment of the body, instead of possess- 

 ing, as does Lumbriciis, only eight bristles per segment, and 

 in having these more or less in couples or pairs on the lower 

 surface. Of course, this is only one out of many features, 

 external and internal, in which the two genera differ, and it 

 is mentioned here as being the chief reason which led Hutton 

 to identify the worms as he did. 



In 1872 a very important memoir on the exotic earth- 

 worms contained in the Paris Museum was published by 

 E. Perrier,* in which he examined his material anatomically, 

 and thereby distinguished among worms with eight chsetee a 

 number of new genera ; but it does not appear that Hutton 

 was acquainted with this memoir at the time he wrote his 

 paper in 1876, and hence arose some of the errors in his 

 identification of the worms of the Otago Museum. Later on 

 he became acquainted with the contents of Perrier's memoir, 

 for in the "New Zealand Journal of Science" (vol. i., 1883, 

 p. 586) he suggests, wrongly, that two of his species of Licm- 

 bricus may belong to Perrier's genus Digaster, while Mr. Smith 

 speaks of some of them as Endrilus, which is probably a 

 misprint for Eudrilus, but neither writer states the grounds 

 for using either of these names. 



During the last fifteen years the literature dealing with 

 earthworms has assumed very large proportions, chiefly at the 

 hands of half a dozen zoologists in Europe ; and, as the 

 number of species and genera have been increased, and the 

 various continents and islands of the world have contributed 

 their quota of material, thanks to the trouble taken by 

 residents and travellers, we have been able to recognise that, 

 just as certain birds and mammals have their special geo- 



* Nouv. Archiv. du Museum d'hist. nat. de Paris, 1872. 



