290 W. B. BENHAM. 



Fig. 7. — Digaster. a. Genital system, ps.^ The anterior 

 sac with penial setae. The posterior sac^ which is described as 

 lying in this somite, is omitted to prevent crowding, pro. 

 Prostate, h. Alimentary system, g.^, g." The two gizzards 

 lying in Somites v and vii. The intra-buccal pepto-nephridia 

 are indicated at ipn, c. The exterior of Somites xvii, xviii, 

 and XIX to show the setae ; male pores represented by black 

 dots, and the openings of the two pairs of sacs with penial 

 setae, ps.^, ps.^, lying one in front of the other. 



Modified from the figures of D. lumbricoides given by Perrier in 

 ' Nouv. Arch, du Mus. d'Hist. Nat. de Paris,' viii, 187^, pi. ii; the modifica- 

 tions being in accordance with Fletcher's description of D. armifera in 

 'Proc. Linn. Soc. N.S.W.,' vol. i, p. 943. 



Distribution : Australia. 



Family II. — Acanthodrilid^. 



Fig. 8. — Acanthodrilus. a. Genital system. Modified 

 from Beddard's figure of A. dissimilis in ' Proc. Zool. Soc.,' 

 1887, p. 388, in accordance with his more recent observations 

 in regard to the independent opening of sperm-duct and pros- 

 tates, ps.^^ ps.^ The sacs of penial setae in Somites xvii and 

 xviii. PRO.^, PRO.^ The prostates in Somites xvii and xviii. 

 h. Alimentary system. 



Modified from Beddard's figure of A. multiporus in 'Proc. Zool. Soc.,' 

 1885, pi. liii. Ca. The fir&t pair of calciferous diverticula, s. Commence- 

 ment of sacculated intestine in Somite xvi. ipn. Intra-buccal pepto- 

 nephridia. The grouping of the nephridial network so as to form eight groups, 

 six of which only are represented, is indicated in Somites xvi, et seq. See 

 Beddard, 'Proc. Zool. Soc.,' 1885. The clitellum in A. dissimilis and A. 

 multiporus commences in Somite xii. I iiave represented it as beginning 

 at Somite xiii, which appears to be more usually the case. c. External view 

 of two Somites, A, B, of A. multiporus, and others in which the eight 

 setse are separate, c, somite of A. novse-zealandiee, and other species in 

 which the setae are in couples. 



Distribution : New Zealand, Australia, West Africa, New 

 Caledonia, Kerguelen Island, the shores of Magellan Strait. 



Fig. 9. — Trigaster. a. Genital system, sp. Sperma- 

 thecae. o. Ovary, pro.^, pro.^ The prostates. Sperm-ducts, 

 sperm-sacs, and testes unknown.^ h. Alimentary system. 

 Slightly altered from my own figures of T. lankesteri in 

 ' Quart. Journ. Micr. Sci.,' xxvii, pi. ix, after a renewed 

 examination as to the position of some of the structures. 



G.', G.^ G.^ The three gizzards, s. Commencement of sacculated intestine. 

 The anterior uepliridial network is more evident than that more posteriorly, but 

 it is uncertain whether there is any communication with the pharynx, c. Three 

 somites seen externally to show the arrangement of the sctre. 



Distribution : St. Thomas, West Indies. 



Michaelsen, however, has in his last paper described the testes and 

 ciliated rosettes iu Somites x and xi, and sperm-sacs in Somites xi and xii. 



