THE INTERNAL STRUCTURE OF ANTS. 



53 



are: first, the infero-internal sensory nerve (warn), second, the supero- 

 external sensory (nans), third, the chordotonal (to acho), fourth, the 

 nerve to the anterior (adductor) muscles of the scape, fifth, the nerve 

 to the posterior (abductor) muscles of the scape (nsc), and sixth, a 

 nerve which supplies the little muscles in the funicular joints (/;/). 

 The tritocerebrum is so much reduced that it is represented only by a 

 pair of small bodies, concealed under the olfactory lobes and connected 

 with each other by a slender commissure, which, however, passes under 

 the oesophagus, thus indicating the originally postoral position of this 

 portion of the brain. Each tritocerebral lobe gives off a nerve which 

 soon subdivides into two branches, one (Fig. 27, cnf ') going to the 



FIG. 27. Sagittal section of head of worker Myrmica rubra. (Janet.) acho, 

 Antennary chordotonal organ ; cnf, connective of frontal ganglion ; art, antennary 

 articulation ; nans, superior antennary nerve ; iiani, inferior antennary nerve ; nf, 

 funicular nerve ; nsc, nerve to scape ; nlr, labral nerve ; soph, sense-organs of pharynx ; 

 in fh, inferior dilator muscle of pharynx ; no, nerves to ocelli ; lies, hypocerebral gang- 

 lion ; mam, adductor muscle of mandible ; Ig, labial sympathetic ganglion ; hi, labial 

 sympathetic nerve; nl, labial nerve; sol, labial sense-organs; nm.r, maxillary nerve; 

 11111, mandibular nerve: s, portions of salivary gland; en, connective between sub- 

 oesophageal and prothoracic ganglion ; nial, adductor muscle of labium. Remaining 

 letters as in Fig. 13. 



frontal ganglion ( to be described below in connection with the sympa- 

 thetic nervous system ) the other again subdividing to innervate the 

 labrum and the wall of the pharynx (;//;-). 



The minute structure of the brain, with its ganglion cells and fibers, 

 the former comprising the deeply-staining, the latter the more achro- 

 matic portions, or " Punktsubstanz " of authors, is too intricate to be 

 considered in the present work. For these details the reader must be 

 referred to the papers of Dujardin (1850). Leydig (1864). Rabl- 



