208 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 
Fig. 
7. Larva of Zumbriconereis, showing the formation of the mouth and first 
body segment (1) below the ciliated band. The two clusters of cells 
above the upper border of the same, near the medial line, are the 
beginnings of cephalic ganglia. (Ventral view.) 
7°. Lateral view of a larva a little younger than the last. 
8. Larval Lumbriconereis older than that shown in Fig. 7. 
9. Still more mature larva of the same, with the rudiments of a second (2) 
and third (8) body segment. 
10. The same larva still more mature. 
11. Larva with three well-defined parapodia and rudiments of two segments 
posterior to the last. 
12. A more mature larva with extended sete and well-developed jaws. 
13. The oldest form of the larval series referred to Lumbriconereis possessing 
seven pairs of sete, the most anterior of which are doubled, while 
the immature forms of new spines can be seen in the more posterior 
segments. 
PLATE VIII. 
Lumbriconereis, Nectonema, and Unknown Genus. 
Anus. 
Ciliated pits on the sides of the head. 
Immature sete at the base of those already formed in the body walls. 
Lateral lines. 
Lower jaw. 
Division between two segments. 
Upper jaw. 
Segmental orifice. 
Body walls. 
3, 4, in Fig. 8°, articulations which together form the lower jaw. Of these 
No. 1 is anterior. 
. 1. Sete and muscular attachments of the same in Lumbriconereis larva. (The 
spine is represented as retracted.) 
2. The same, extended. 
3. Larval Lumbriconereis with three parapodia. 
4-10. Nectonema agilis Verr. 
4. The adult Nectonema. 
Enlarged view of the head of the same. 
The head from dorsal side. 
Clear space with contained cells (ova ?) in the head. 
The same from dorsal side. 
Magnified view of a section of the lateral line, destitute of lateral spines 
and “connecting web.” These last structures were not found in this 
specimen. 
SOFT OS CK 
“10. Posterior end of the body (¢ ?). 
“11. Cephalotrix linearis (young). 
“12-14. Three larval stages in the development of a mesotrochal Annelid, 
probably Telepsavus or Phyllochetopterus. (Younger than those 
figured in Pl. III. See text.) 
