16G Transactions. — Zoology. 



" There is another cliaracter to which comparatively Httle 

 attention has been paid which may prove to distinguish the 

 genera Benliamia and Acanthodrihcs . In the tw^o species of 

 Benhamia described in the present paper, as well as in B. 

 siiihlmanni, there are no setce upon the eighteenth segment 

 where the ventral pair should be ; these setae are also absent 

 from the seventeenth and from the nineteenth segments, or, 

 rather, they are there replaced by the penial setae. In all the 

 species of AcantJiodrilus, on the other hand, which I have been 

 able to examine, the ventral setae are not missing from the 

 eighteenth segment, though they are not present on the seven- 

 teenth and nineteenth segments, being there replaced by the 

 penial setae. This is also the case with the genus Octochatus ; 

 in two of the species of that genus, at any rate — viz., O.multi- 

 porus and 0. antarcticus — the ventral pair of setae of segment 

 xviii. are present and quite normal ; on segments xvii. and 

 xix. the ventralmost seta is present and unmodified. Octo- 

 chcBtus antarcticus is, furthermore, remarkable for the fact 

 that the setae of the seventeenth and nineteenth segments ap- 

 pear at first sight to be present and normal ; as a matter of 

 fact, the outer seta of the ventral pair is replaced by the 

 penial setae, which occur exceptionally in this species. These 

 setae a,re very much smaller than in Acanthodrilus dissimilis, 

 for example, and can hardly be seen until they are examined 

 microscopically, but they are undoubtedly there. The ventral- 

 most seta of the ventral pair is not absent from these seg- 

 ments as it usually is, but is quite recognisable. This species- 

 is, therefore, in a less modified condition than is any other of 

 the species of Octoclicetus, or Acanthodrilus, or Benliamia. In 



A. annectens and A. yaludosiis, described in the present paper,, 

 there is, as in Octoclicetus, a single seta ventrad of the atrial 

 pores. 



" In all the species of Benliamia which I have dissected, 

 the calciferous glands are different from those of Acanthodrilus 

 or OctochcBtus. These glands are, in Benhamia, reniform 

 pouches attached to the sides of the oesophagus ; in Acantho- 

 drilus and Octoclicetus these glands present the appearance of 

 swellings upon the course of the oesophagus. Moreover, in 

 Benhamia there always appear to be three pairs of calciferous 

 glands, which may, perhaps, prove to be always in segments- 

 XV., xvi., and xvii.; they have been for the most part described 

 as in these segments, and it is possible that in those cases {e.g., 



B. buttikofcri, Horst) where they are stated to occupy the 

 fourteenth, fifteenth, and sixteenth segments a mistake of one 

 segment may have been made ; anyhow, the three pairs seem 

 to be characteristic, and nearly, if not quite, universal. 



"The species Acanthodrilus novce-zealandice, A. assimilis, 

 A, rosea, and A. smitlvi (to be described in the present paper), I 



