20 Annals of the South African Museum. 



duction ; in fact, in two of the specimens the first pair of gills is 

 wanting, and in the third the first right gill is absent and the first 

 left one minute. The longer axes of the middle gills are about 

 2-5 mm. in length. The gills are of the pinnate type. 



A striking feature of all the specimens is the presence of only five 

 pairs of nephridiopores, which are situated on the fifth to the ninth 

 segments inclusive. I have previously examined more than twenty 

 specimens of this species from the Falkland Islands, South America, 

 Tasmania, and New Zealand, in all of which, except two, six pairs 

 of complete nephridia are present ; though in several cases the first 

 pair is smaller than any of the others. In one of the two specimens 

 just mentioned, the first nephridium of one side is complete, but that 

 of the other side has no funnel, and in the other example the first 

 left nephridium is wanting and the first right one is represented only 

 by its terminal vesicle. The specimens from Luderitzbucht and 

 Table Bay illustrate a further step in the reduction, for none of 

 them possesses a nephridiopore on the fourth segment. The apertures 

 of the other nephridia, on the fifth to the ninth segments, are readily 

 seen in these specimens, which have been killed in an expanded 

 condition, so that the absence of pores on the fourth segment is 

 ascertainable with certainty. Dissection of two specimens from 

 Luderitzbucht and one from Table Bay confirms the absence of 

 nephridia from the fourth segment. 



There are comparatively few segments about ten to sixteen in 

 the tail, and they are only feebly marked off from each other 

 externally. The tail is less muscular than that of A. loveni. 



INTERNAL ORGANS. 



These need not be described in detail here,* but reference may be 

 made to a few outstanding features. The three septa are present 

 as in other species of Arcnicola, at the anterior end of the first; 

 third, and fourth chcetigerous segments. Septal pouches are not 

 present in this species. 



Oblique muscles are present from the first or second chaBtigerous 

 annulus to the end of the tail. 



There are several glands on each side of the posterior portion of 

 the oesophagus, namely, a long anterior one, and usually seven or 

 eight smaller behind this, but one specimen has a long and fifteen 

 short caeca on each side. 



* An account of the anatomy of A. nsfsimiUs, by the present writer, will be found 

 in Quart. Journ. Micr. Sci., vol. 46, pp. 74Q-759, 1903. 



