OCR Text |
Show 1885.] NEW-ZEALAND EARTHWORMS. 813 in which there are four male generative apertures is Moniligaster, but in this genus the position of the orifices is different, and the anatomy of the worm is in other respects quite different from that of Acanthodrilus. ACANTHODRILUS NOV^E ZELANDI^E, n. sp. Setae disposed as in Lumbricus in four series of pairs. Clitellum occupies 8 segments (12-19 inclusive); it is saddle-shaped, having a ventral area upon which there is no glandular development; on segments 16 and 18, corresponding to ventral row of setse, are male genital apertures through which penial setse protrude. The apertures of the copulatory pouches are between the 6th and 7th and between the 7th and 8th segments. The apertures of the oviducts are paired, and upon the 14 th segment. The apertures of the nephridia alternate in position from segment to segment, sometimes they are in front of the dorsal, sometimes of the ventral pair of setse. The nephridia are furnished with a long muscular duct and a minute diverticulum, or have a large diverticulum and no muscular duct; the former are the dorsal series, the latter the ventral. The dorsal vessel is formed of two trunks anteriorly, which unite where they perforate the intersegmental septa. Tbe intestine is unprovided with caeca or glands of any description. The testes are two pairs of racemose glands in segments 11 and 12 ; the vasa-deferentia funnels open in segments 10 and 11 ; the external apertures of the vasa deferentia are accompanied by a bundle of penial seta? and long coiled tubular prostatic gland ; the ovaries are in segment 13 ; the oviducts perforate the mesenterv, dividing this from segment 14. There are two pairs of spermathecse in segments 7 and 8 ; each is a round sac with a short duct, round which are clustered a group of accessory diverticula. ACANTHODRILUS DISSIMILIS, n. sp. This species is very closely allied to the last, and only differs, so far as I have been able to make out, in two points. The dorsal vessel is a single tube, and the copulatory pouches are furnished with only a single pair of large diverticula, one on either side. ACANTHODRILUS MULTIPORUS, n. sp. This species differs considerably from the two last. Like A. nova zelandia, it attains to a length of from 10 to 12 inches and ^ an inch in diameter. The setse are disposed in eight equidistant rows of a single seta each. The clitellum occupies the same segments as in the last species, and the male genital apertures have the same position and correspond to the outermost of the two ventral setse ; there are no special penial setse. The apertures of the spermathecse are between 7 and 8 and between 8 and 9 ; they correspond in position to the outermost of the two ventral setse. The spermathecse appear to be simple spherical pouches without anv diverticula. The nephridia are small and delicate ; each segment is furnished with 8 nephridial pores corresponding to the 8 setse ; P R O C Z O O L . Soc-1885, N o . LIII, 53 |