534 



open in front of the ventral setae of the fifth segment. In all the spe- 

 cimens which were examined there were invariably two setae 

 only in each of the ventral bundles of the fifth segment; 

 whereas in the segments anterior to the fifth the number was not con- 

 stant, being either two or three ; the setae of the fifth segment were in 

 no particular different in shape from those of other segments. 



The atria open on a line with the sperraathecal apertures on to 

 segment VI. Dero appears to differ from other Naidomorpha e. g. Nais 

 in the fact that the ventral setae of this segment are entirely 

 absent. In Nais elinguis according to Vejdovsky^ and Stolc^ the 

 atrial apertures are furnished with special genital setae, and the same 

 structures are present in the few other species of Naidomorpha which 

 have been investigated in the sexual condition. 



There is a single unpaired sperm sac and egg sac. 



2) A species of Perichaeta from Borneo. 



Up to the present time the only earthworm which has been de- 

 scribed from this island is Megascolex armatus. I noAv am able, through 

 the kindness of Mr. H. O. Forbes, to refer to certain peculiarities 

 in the structure of a large species of Perichaeta from the same island. 



I reserve a full account of the anatomy of this Perichaeta, which 

 exhibits one peculiarity of some interest, which I have not noticed or 

 seen referred to in any other earthworm. 



In both of the two individuals at my disposal the spermatheca 

 showed a marked asymmetry. On one side of the body (the left 

 in both specimens) there were two spermathecae placed close together 

 in the VIIP^' segment. On the right hand side of this segment tliere 

 was only a single spermatheca, and a single pair, one on each side of 

 the body, in the following segment. This peculiarity if it had been ob- 

 served in only one specimen, would naturally be regarded as an abnor- 

 mality; but its occurrence in two specimens selected at random, seems 

 to be a strong proof that it is normal. 



3) Note on Moniligaster. 

 Dr. D. Uosa in a valuable paper upon the Classification of Earth- 

 worms'* has criticized some statements of my own*^ concerning the 

 structure of the remarkable genus Moniligaster. Rosa points out that 

 two much stress was laid upon the apertures of the vasa deferentia 



3 1. c. 



* Zool. Anz. 9. Jahrg. p. 504. 



•'' Boll. Mu3. Zool. Anat. Comp. Torino. Vol. 111. No. 41. 



6 Zool. Anz. No. 268. 



