ON A NEW SPECIES OF APHRODITA. 



By T. Harvey Johnston,- M. A., B.Sc, Parasitologist, Bureau of 

 Microbiology, Sydney; Hon. Zoologist, Australian Museum. 



(Plate Ixix., tigs. 1-8.). 



There are in this Museum a number of Polychretes formerly 

 labelled Aphrodita austral is, Baird 1 . The original description 

 of this species is sufficiently general to include several allied forms. 

 Prof. W. Mcintosh, 2 however, gave a much better description, 

 accompanied by figures, of specimens collected off Port Jackson 

 by H. M.S. " Challenger." As he had examined Baird's type in 

 the British Museum, we may safely take his description as a 

 means for comparing our own worms with A. australis. 



The animals are apparently distinct. Both possess forty-two 

 segments, which narrow very rapidly towards the posterior 

 extremity. Our type, an adult female, is seventy-five milli- 

 metres long ; its greatest width (excluding the setse) is in the 

 region of the tenth, eleventh and twelfth segments, being thirty- 

 two millimetres. The posterior fifteen segments total only nine 

 millimetres in length. The region of greatest width is more 

 anteriorly situated than is shown in Mcintosh's figure. 



The prostomium or head is very small, rounded, and completely 

 covered by the anterior pair of elytra. The median tentacle is 

 very short, being almost rudimentary. It is more rounded than 

 in A. australis. There are two pair of simple, sessile, black eyes, 

 the anterior pair being much larger and more darkly pigmented 

 than the posterior. The latter are situated above and behind 

 the former (PI. Ixix., tig. 2). The eyes are directed fowards, 

 their appearance from the front being on PI. Ixix., fig. 3. 



The first stigerous segment (peristomium) is visible dorsally on 

 removing the elytra, as a collar- like ridge behind the prostomium. 

 The scales of the next segment completely overlap this segment 

 and the hea<l. Extending forwards from below the tentacle is 



1 Baird — Monograph of the Aphroditidse Jouin. Linn. Soc, Zool , x., 

 1865, p. 17b). Haswell — Mod. Australian Aphroditea (Proc. Linn. 

 Soc. N.S. Wales, vii., 1S82, p. 250). 



2 Mcintosh— Polychata (Chall. Rep., Zool., xii., 18S5, p. 34). 



