PLATE 3. 



All figures are from methylene-blue preparations. 



FicrRE 11. Branohiostoma lanceolatum. The first and second (second and 

 third of Hatschek) myomeres, ?hi, and m2, and the proximal por- 

 tions of nerves I, II and III, of the right side. Nerve II .shows 

 two roots and perhaps a third (between II and IIi). X 84. 



Figure 12. B. lanceolatmn. The first and second myomeres, nii and nii, 

 and the proximal portions of nerves I, II and III, of the left 

 side. Nerve II shows two roots (II and IIi); o. olfactory 

 pit. X 84. 



Figure 13. B. lanceolatum. The visceral rami of a dorsal nerve, viewed 

 from the interior. The branches supplying a gonadial pouch 

 {hrs. gon.) are shown. The larger meshes of the plexus on 

 the interior (median) surface of this pouch are drawn. The 

 place of emergence of the visceral ramus on the internal 

 surface of the side muscles is indicated at a. The branches 

 i, i, from ramus visceraUs descendens pass to the gonadial 

 pouch. The ventral muscle border is indicated at m. v. X 

 123. 



Figure 14. B. lanceolatum. A nerve plexus on a secondarj' branchial bar, 

 not far from the ligamentum denticulatum, viewed from the 

 external (lateral) surface of the branchial basket. Branchial 

 nerves of the anterior part of the animal. X 254. 



