KM. TvrnhnU — Anatomy and Habits of Nereis vlrens. 277 



smaller ganglia joined together. It bears tlie eyes, on fo\ir short ner- 

 vous peduncles, on its dorsal side. In front it sends four nerves to the 

 antennje (/>, b and c, c, iigs. 27 and 28). Laterally it sends out 

 two branches called the connectives [d, d), which pass around 

 the mouth and proboscis to join the first of the abdominal gan- 

 glia (A, tig. 27). Near the junction of the connective with the 

 head ganglion, is a small ganglion sending nerves to the internal 

 tentacular cirri (e, e, figs. 27 and 28). The connectives, near their 

 lower extremity, send two nerves {g, g, fig. 27) to a series of ganglia 

 and nerves on the ventral side of the proboscis {to, w, fig. 27). There 

 is also an accessory connective (figs. 27 and 28, d') on each side, })ass- 

 ing from the first abdominal ganglion to the ganglion supplying the 

 external tentacular cirri {e',e', figs. 27 and 28). This accessory connec- 

 tive also has a ganglion {ii\ fig. 27) at the middle, sending nerves to 

 the muscular partitions of the proboscis. 



Each of the first three abdominal ganglia sends, from its anterior por- 

 tion, on each side, a nerve that forks, one branch (fig. 27, n) going to the 

 muscular partition and the other (o) passing through the partition to 

 the preceding segment. In the remaining abdominal ganglia, begin- 

 ning with the fourth, the branches ti and o become separate nerves 

 (fig. 27). From the posterior portion of these ganglia a nervous trunk 

 on each side (w), goes to each foot, where there is a small ganglion 

 (k) sending off a cutaneous branch and a branch (^), supplying nerves 

 to the foot. 



The ganglia (fig. 28, e, e) and the head-ganglion {a) send some very 

 slender nerves (fig. 28, 2, z) to a series of ganglia on the dorsal side of 

 the proboscis (y, y). In figure 27 the series of ganglia {ii\ w) are 

 drawn as if the proboscis had been revolved about a line drawn 

 through its anterior end, so that the ventral surface would be upper- 

 most. In figure 28 the ganglia (y, y) are in their natural position. 

 The dorsal ganglia (fig. 28, x, x) are connected with the ventral 

 ganglia (fig. 27, v, v) by means of nervous cords; the dorsal ganglia 

 (s, s, fig. 28) with the ventral ganglia (fig. 27, 1, 1), by means of nerves 

 [)assing around the proboscis outside the points of the retracted jaws 

 (/,/); and the dorsal ganglia {t, t, fig. 28) with the ventral ganglia 

 (^5 p, fig.27) by means of two short, thick nervous commissures which 

 send off the nerves {k, u, figs. 27 and 28). These two nerves {((, u) 

 terminate in the ganglia (r, r, figs. 27 and 28). 



These gangba and iierves of the proboscis lie on its walls, under- 

 neath the muscles. 



