598 PROCEEDINGS OF THE AMERICAN ACADEMY. 



alKloininal plexus as sympathetic. According to Rolion, the l)ranchial 

 nerves end in tufts. Fusari (p. 133) differs from this, and states that 

 they spread out in a membrane that covers and supports the branchial 

 apparatus on its external surface. On this membrane the different 

 nerve branches form a net of irregular meshes, which Fusari calls the 

 nerve net of the branchiae (his Taf. Mil, Fig. 2). This figure proba- 

 bly illustrates a plexus formed by ascending visceral branches before 

 they reach the branchial basket (compare PI. 4, Figs. 15, 16). Fusari 

 probably saw a nerve net distributed over the gonadic pouches. 

 Heymans et van der Stricht ('98, p. 41-44) describe in detail the 

 branches of the rami viscerales ascendentes, and figure nerves in the 

 ligamentum denticulatum, a small number of fibers on the branchial 

 bars, and fibers on the cross bars, joining those running lengthwise of 

 the primary and secondary bars (their Fig. 30). These authors also 

 figure a plexus distributed along the median ventral portion of the 

 branchial basket, and show a portion of a plexus covering the gonads. 

 They never found nerve fibers in the interior of the branchiae. They 

 note a plexus in the ligamentum denticulatum, parts of which resemble 

 a longitudinal ner\-e trunk; but in their opinion an actual large longi- 

 tudinal nerve does not usually exist, except as formed indistinctly by 

 the anastomosis of different branches of the ascending visceral nerves. 

 These authors are therefore inclined to deny the existence of a distinct 

 vagus nerve. Other branches of the rami viscerales ascendentes were 

 observed, which these writers (PI. Mil, Fig. 26) regard as perhaps 

 innervating the blood-vessels, digestive tube, and the parietal serous 

 surface of the branchial cavity. Dogiel ( : 02) presents figures of Golgi 

 preparations showing numerous fibers on the primary and secondary 

 l)ranchial bars, and on the cross bars; also nerve cells of spindle-like 

 or angular shape, previously undescribed, possessing from three to 

 six processes, which gradually divide into a great number of twigs. 

 Dogiel finds such cells in all parts of the branchial basket, and regards 

 them as analagous to the sympathetic cells in the intestinal plexus of 

 the "Xeunauge" (river-lamprey). He also finds ascending visceral 

 branches posterior to the Ijranchial l)asket, which he is certain supply 

 the intestinal canal (Fig. 17a, 176, 18a, 186, 19a, and 196). 



My own observations on the ascending visceral nerves and their 

 branches were made chiefly from specimens of B. lanceolatum, only a 

 few individuals of B. caribaeum pro^•ing fa\-orable for study of these 

 nerves. Dissected specimens previously impregnated with methylene 

 blue were particularly useful in following the ramifications of the rami 

 viscerales ascendentes. A studv of these nerve branches is attended 



