112 CAUDAL GILLS OF ZYGOPTERID LARVAE. 



Fig.41,— TS. through right lateral gill of same, at same level as fig. 40; 

 (x87). 



Fig. 42. - T.8. through median gill of .same, at about one-third of the gill- 

 length from the base; rachi.s and small portion of blade onlj'; 

 ( X 207). 



Fig 43. — T.S. through same gill as tig. 48 taken far distad. to show con- 

 fluenee of dm'sal and ventral blood-eanals; nnicli of the blade 

 <miitted;( x207). 



Fig. 44. — A detail from .same .series of .sections as figs. 40-43, much enlarged, 

 to show portion of hypodermis and cuticle, ecto- and endotrachea 

 of the left main trachea, two nuclei in the alveolar mesh work and 

 the right dorsal longitudinal nerve. The figure is shown inverted, 

 as drawn under the microscope. It coi responds with the part of 

 the gill marked .r in fig. 40; ( x 833). 



Fig.4o. — T.S. through a longitudinal nerve (vr} and neighbouring alveolar 

 nucleus {a/n). The section cuts the nerve so as to pass through 

 two nuclei; ( x 12o0). 

 N.B. — With the exceptions of rigs.31-33 (from Ris), all the figures in 



Plates iii.-vi., are wash-drawings made from eamera-lucida drawings of 



double-stained, lOtx sections. 



