METCALF. [VOL. I. 



EXPLANATION OF FIGURES. 



Reference Letters. 



a.s.n. anterior siphonal nerve. 



d. = duct from neural gland to ciliated funnel. 

 f.r.n. = fibers of rapheal nerve. 



g.c. = cord of ganglion cells. 



gg. - ganglion (brain). 



gl. = neural gland. 



g.r.n. = ganglion cells of rapheal nerve. 

 p.s.n. = posterior siphonal nerve. 



r.d. = rapheal duct. 



r.n. = rapheal nerve. 



The figures are diagrammatic parasagittal sections of the ganglion and neural 

 gland, a little to the right of the median plane. In Figs. 4 and 5 the rapheal 

 duct, which in reality lies on the right surface of the ganglion, is shown, although 

 in reality it lies much to the right of the plane of the rest of the section. 



FIG. i. Cynthia papillosa. 



FIG. 2. Distaplia magnilarva. 



FIG. 3. Amaroecium constellatum. 



FIG. 4. Ascidia atra. 



FIG. 5. Phallusia mammillata. 



