MR 



ON SOME LOWER ANNELIDS. 645 



AUTHORS REFERRED TO. 



V. Baer. Nov. Act. Curios, xiii. 1826. 

 Baird. Catalogue of Worms, p. 71. 1865. 



Claparkde. Beobachtungen iiber Anat. und Entwickelungsgesch. d. wirbellosen Thiere. 186i'. 

 Claus. Wiirzburg. naturwiss. Zeitschr. Bd. i. (I860), p. 37. 

 Eerenberg. Symbols Physicse seu icones et descript. &c, (Libya) iv. 1828. 

 Grube. Die Familien der Anneliden, p. 101. 

 (xruithuisen. Nov. Act. Acad. Leop. Carol, vol. 14, 1828, p. 407. 

 Leydig. Lehrbucb der Histologie. — Archiv fiir Anatomie, 186o.< 

 Maggi. Intorno al genere JEolosoma* Milan, 1865. 

 Muller. Vermes, i., ii. 20. 1771. 



Schmidt. Archiv fiir Anatomie, 1846, p. 406. — Sitzungsber. Kais. Akad. Wien, vol. xxiii. 1857. 

 DTdekem. Bull. Acad, de Belg. t. xxii. part 2, 1855, p. 553; ib. ser. 2, t. xii. p. 243, 1861.— Mem. dcs Sa? 

 etrang. publ. par PAcad. de Belg. t. xxvii. 1856. 



(PliltrS) 



EXPLANATION OF THE PLATES. 



Plate XLYIII. 



Fig. 1. Chmtogaster limnm, v. Bar. A chain of zooids, consisting of two nearly complete individuals, each 



of which has produced segments posteriorly. The worm is not compressed by the covering-glass ; 

 and the foot-like appearance of the bristle-bundles, and their implantation, are well seen. Natural 

 size =£ inch. 



Fig. 2. A ventral view of the third pair of abdominal bristle-bundles. The worm is stretched, uncom- 

 pressed, and the booklets are directed outwards and downwards. They may be directed inwards 

 and upwards, and some in one, some in the other direction. 



Fig. 3. An outline of a ventral view of a specimen similar to that drawn in fig. 1. The head is very much 



extended, as is frequently done in search of food. 3 a. A lateral view of a specimen in the act 



of crawling. 



Fig. 4. Probably the early stage of JEolosoma quaternarium, Ehrenberg. 



Fig. 5. JEolosoma quaternarium, Ehrenberg. 



Fig. 6. Lateral view of the head of the same. 



Fig. 7. Supposed section to show the position of the bristle-bundles. 



Hg. 8. Two setae from the ventral (neuropodaD series. 



1 



eus. Ehrenberg, showin 



Fig. 10. Chatogaster niveus, Ehrenberg. A furrow is seen below the third pair of abdominal bristle- 

 bundles, apparently indicating the future independence of the two succeeding segments. 

 Fig. 11. Setae of Chcetogaster niveus, Ehr. Compare figs. 15 & 16. 

 Fig. 12. A ventral view of Ch. limnm. A little compressed and 



The 



ammatic 



„_ o The letters have the following signification :—/w, prostomium; pr.g, 



prostomial ganglion (seen indistinctly) ; m, mouth ; pc, palpocils (on warty tubercles of the 

 integument) ; c. b, cephalic bristles (12 in a bundle) j n, nerve-band; lp.v, lateral 

 vessel ; ph, pharynx j I c.v, lateral commissural vessel (from the dorsal to the ventral i 



pharyn 



stomach : v. v, ventral vessel (ly 



bundl 



band) j 1 seg, 1st segment 



bristles 



bristle 



bundle) ; /. d, lines of demarcation 



caused by deep grooving of the surface ; c. b. d, cephalic bristles commencing development 



