EXPLANATION OF PLATES XLVII TO LVIII. 



COLORS. 



The dark blue ink in which the plates are printed represents those portions that 

 stain deeply with Kleinenberg's hsematoxylin, i. e., cell walls, basement membranes, 

 chromatin fibers of nuclei, protoplasmic granules, etc. 



Light blue = central nervous system, also certain mesoderm elements, blood cor- 

 puscles and spindle cells, in the neighborhood of the ganglion. 



Grayish violet = ectodermal epithelium. 



Light green = epithelium of the wall of the pharynx or cloaca and of the sub- 

 neural gland. Owing to a mistake in the final printing, this color is hardly distin- 

 guished from the too deep yellow. 



Yellow = body cavity, usually more or less filled with coagulum and scattered 

 connective tissue elements. The larger blood spaces are frequently left uncolored. 



Keddish brown = pigment. 



REFERENCE LETTERS. 



a = lateral lobe of the dorsal eye of Salpa cylindrica. 



an = antero-dorsal angle of the ganglion in Salpa scutigera-confederata, or its 

 homologue in other species. 



b = small celled, ventro-lateral outgrowth from the ganglion toward h. 



b' large celled, ventro-lateral outgrowth from the ganglion toward h. 



be = blood corpuscle. 



bl = blood lacuna. 



cf= ciliated funnel. 



cr non-cellular core of the optic ridge. 



d lateral duct of the subneural gland. 



(/' = remnant of the right lateral duct of the subneural gland in Salpa cylindric;i. 

 chum form. 



dl dorsal lamina (gill or its anterior curtain-like projection). 



do opening of the lateral duct of the subneural gland into the branchial 

 chamber. 



e = eye or rudiment of the eye. 



e' = basal portion of the unpaired eye of the chain form. 



e' I, e' 2 = two portions of e', found in Salpa democratica-mucronata, chain form. 



e" = apical portion of the unpaired dorsal eye of the chain form. 



e'" = secondary portion of the unpaired dorsal eye of the chain form. 



eq = antero-ventral enlargement of the retina of the solitary Salpa runcinata- 

 fusiformis. 



ex = one of the dorsal pair of small eyes in the chain Cyclosalpa pinnata, or its 

 homologue in other species. 



ey one of the posterior pair of small eyes in the chain Cyclosalpa pinnata, or its 

 homologue in other species. 



/ = canal of the central nervous system. 

 /' = communication between / and I. 



f 1 = canal of the duct between the ganglion and the funnel. 

 g ganglion. 



