570 MEMOIRS OK THE NATIONAL ACADEMY OF SCIENCES. 



PLATE LVII. 

 (Stage Xll.) 



FIGS. li36--'45. Horizontal sections of first larva, illustrating further the anatomy of the alimen- 

 tary tract and the nervous system, x tf. 



REFERENCE LETTERS. 



A. I, II, first auil second antenna. 

 ag. . green gland, 

 a/., autennular fiber-mass. 

 ao., ear. 



by., branchiostegite. 

 Kiid., eudoderm. 

 fy., foregut. 



fo., fiber-substance of CBSOpbageal commissure. 

 ijf., fiber-mass of second antennae. 



gg. '~ :1 , middle, ventral, and dorsal divisions of posterior lobe of midgut, 

 till., hinilgut. 



//., lateral fiber mans of brain. 

 Md. , mandible. 

 .)/;/., midgut. 



-Vo.', lateral lobe of uiidgut. 



MIL, nartition between anterior lobes of midgut. 

 Mts., mi'taistoma. 



l/i . /, //, first and second maxilla*. 

 Mspd. I-lII, first to third maxillipedo. 

 . i(., aiiti-uniilar nerve. 

 H.C., ventral iierve-cord. 

 of., anterior fiber-mass of brain. 

 017., optic ganglion. 

 /,'' /., retina. 



n. l-V, first to fifth ambulatory limbs. 

 y., yolk. 



