218 PEOF. W. B. BENHAM ON AQUATIC [NoV. 3, 



Remarks. — In 1889 (P. Z. S.) Mr. Bedclard recorded the occur- 

 rence in New Zealand of " Limnodrilus sp. inc.," but gave no 

 details as to its anatomy ; but in 1892 (P. Z. S, p. 354) he states 

 that the New-Zealand Limnodrilus possesses two pairs of greatly- 

 dilated hearts in segments viii., ix. In his Monograph, p. 247, 

 he repeats this; and both on this page and p. 230 he refers 

 to this worm as " L. novcBzelandice." Possibly this is a MS. name 

 and crept into the Monograph unintentionally ; but it is regrettable 

 that no further details have hitherto been published, and as his 

 specimens are stated to be immature, it is probable that we shall 

 never know what " L. novcezela7idice " is : it is a name that has to 

 disappear. It is quite likely, of coiu-se, that the present "species" 

 is identical with Beddard's, and I hope to obtain more material 

 before giving it any name. 



In view of the general distinctness between the lacustrine worms 

 of the Northern and Southern lakes, it is possible that two species 

 are included here; but in the immature condition I detect no 

 peculiarity sufficient to differentiate them. 



In looking up the literature dealing with the genus Limnodrilus 

 and other Tubificids, I have been struck M'ith the paucity of 

 information, on many anatomical points, about the common Euro- 

 pean species. It seems to me desirable to have some information 

 as to the amount and degree of variation that may occur in the 

 form of the chsetse of Limnodrilus, so as to be able to ascertain 

 how far the relative size of the two prongs is a reliable specific 

 character. 



Another point that requires attention is the extent of the 

 clitellum in different species of Tubificids, for in Michaelsen's 

 and in Beddard's Monographs little attention is paid to this point ; 

 and since in the Earthworms it is of value in identification, it 

 seems likely that here, too, it would have a certain, but pei-haps 

 more limited, value. 



It is only in the case of those species that have been examined 

 in recent years that this point has been determined. In neither 

 monograph do I find a statement as to its extent, for instance, in 

 the common European species of Limnodrilus, and, indeed, in very 

 few members of the family. Beddard (p. 85) in a tabular state- 

 ment showing the position of the genital organ in the various 

 families of the Oligochseta, writes under the heading " clitellum ": — 



"Tubificidfe 10, 11." 



But in the discussion on the characters of this family, further on 

 in the volume, it is not stated, either explicitly or implicitly, 

 whether the comma between the two numerals stands for the 

 word " and " or " or " ; and no details as to the point in question 

 are to be found in the account of the genera or species of the 

 family. But from the few records that we have, it is evident that 

 in the family Tubificidse the clitellum is not limited to one or even 

 to both of these segments, and it is more extensive and variable in 



