162 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 7 



the common west coast species. L. grandis Treadwell, from Hawaii, is 

 less obviously so chiefly because maxilla III is shown with a single 

 tooth instead of two. The description of L. sarsi Kinberg, from Ecuador, 

 is too brief to permit a comparison of details. An investigation of the 

 type might reveal its identity. If, as seems likely, these names refer to 

 a single, widely distributed species, we may expect L. brevicirra to occur 

 on both sides of the Pacific, and in both northern and southern hemi- 

 spheres. 



Developmental stages. — During February various stages of L. brevi- 

 cirra are obtainable in southern California. The large, light green, 

 spherical eggs (pi. 29, fig. 10) are laid in the burrow, without a gelati- 

 nous sheath or other investing membrane, and the larvae develop there. 

 The eggs are up to 0.5 mm in diameter. How they leave the body 

 cavity is not known, but obviously not by rupturing the body wall. 

 Well over 100 have been observed in the burrow of one individual. 

 The stage of development is approximately the same for all individuals 

 in any one tube. 



The earliest setigerous larva has 3 segments (pi. 29, fig. 9), each 

 segment with a single pair of limbate setae. Most of the space posterior 

 to the prostomial lobe is filled with green yolky material. The prosto- 

 mium has a pair of diffuse dark spots, and another dark area where 

 the maxillary parts will develop (pi. 29, fig. 9). Ciliary bands are ab- 

 sent save for some short cilia about the oral area. 



Increase in length is accompanied by an increase in the number of 

 segments and development of the alimentary tract. In an 8-segmented 

 larva (pi. 29, figs. 7, 8), still bright green, the proboscidial area is 

 well developed (pi. 29, figs. 7, 11), the parapodia are lateral prolonga- 

 tions provided with both limbate setae (pi. 29, fig. 5) and hooks (pi. 

 29, fig. 6), and the alimentary tract is complete. Cilia are present only 

 around the mouth. When isolated, these larvae forage for themselves, 

 and secrete a mucous sheath in which they lie. 



The incidence of setae in an 8-segmented larva is as follows: first 

 segment with 2 limbate setae; second segment with 3 limbate setae and 

 1 hook; third and fourth segments each with 2 setae and 1 hook; fifth 

 to eighth segments each with 1 seta. In the adult specimen from which 

 these larvae are taken, the arrangement of setae is as follows, counting 

 from dorsal to ventral positions: first segment with 4 limbate setae, 1 

 simple hook, 1 seta; second segment with 3 setae, 2 simple hooks, 1 

 seta; third to twenty-eighth segments with similar arrangement as in 



