| OCR Text |
Show 1887.] NEW GENUS OF LUMBRICID.E. 161 which is so well marked in Urochata and in Acanthodrilus multiporus, is, as it were, just commencing in Thamnodrilus. (2) The next fourteen pairs of nephridia (see fig. 5) open on to the exterior of the body in a line with the dorsal pair of sette ; the most anterior nephridia are rather smaller than the posterior pairs in corresponding with the increasing width of the segments. The glandular part of the nephridium is very slightly developed in comparison with the extremely elongated muscular sac which communicates with the exterior ; at the junction of the two regions of the nephridium, the Fig. 6. One of the Posterior Nephridia. Lettering as in fig. 5. muscular duct becomes dilated and bent slightly upon itself; its walls become glandular ; this portion of the gland is distinguishable by its opaque white appearance. (3) From the 17th segment to the end of the body the nephridia are of a somewhat different character to those which precede them ; the muscular sac of the gland is well developed and opens on to the exterior at the same point as in the anterior segments ; it differs in being furnished with a diverticulum which is nearly as long as itself; the glandular region of the nephridium is more PROC. ZOOL. Soc-1887, No. XI. 11 |
