SARGENT: THE OPTIC REFLEX APPARATUS OF VERTEBRATES. 209 



trunks have been traced cephalad nearly to the base of the ganglia 

 habenulae. 



Stromateidae (135). In the young butterfish, Rhombus triacanthus, 

 15 mm. long, the torus longitudinalis is well developed anteriorly 

 (Plate 7, Fig. 50). The growth of the valvula cerebelli forward into 

 the mesocoele has resulted in the crowding forward of the torus so that 

 the latter lies almost wholly dorsal to the posterior commissure, and 

 within the anterior prolongation of the mesocoele above it. Eeissner's 

 fibre is formed very largely from trunks emerging from the ' Schaltstuck * 

 anterior to the commissure (trt. tor. fbr. Reis. a.). In addition there 



Figure I. Poniatomus saltatrix, adult. Sagittal section of the dorsal portion of 

 the midbrain. For meaning of abbreviations, see Explanation of Plates, 

 p. 257. 



are clearly some finer trunks which emerge from the anterior extremity 

 of the ' Schaltstuck/ and probably have their origin in the ganglia 

 habenulae. In the mesocoele below the valvula, Reissner's fibre is 

 fully consolidated and 0.7 micron in diameter. In the closely related 

 Eupomotis gibbosus, the conditions are practically the same as in 

 Rhombus. In the adult the diameter of the fibre is 3 micra. 



Serraxidae (14G). Of this family I have studied the apparatus in 

 the adult of the white perch, Morone americana (Plate 10, Fig. 68), and 

 the sea bass, Centropistes striatus. In both, the importance of the 

 apparatus is evidenced by the size of Reissner's fibre. In the perch its 



