Plate 5. 



Figs. 18-20. Macrurus canus Garman. 



Fig. 18. The fish seen from the side. Drawing ; natural size. 



Fig. 19. A radiating disc in transmitted light. Photograph; magnified 1 : 11. n, main 



disc nerve ; p, branched pigment cells. 

 Fig. 20. A radiating disc in transmitted light. Photograph; magnified 1 : 17. n, main disc 



nerve; p, branched pigment cells. 



Figs. 21-23. Myctophum aurolaternatum Garman. 



Fig. 21. The fish seen from the side. Drawing; natural size, al, anterior lateral radiating 

 organs; ma, mandibular radiating organs; ml, mediolateral radiating organs ; 

 op, opercular radiating organs; pe, pectoral radiating organs; pi, posterior 

 lateral radiating organs; va, anterior vontroanal radiating organs; vc, ventro- 

 caudal radiating organs ; ve, ventromedial radiating oi'gans ; vp, posterior ven- 

 troanal radiating organs. 



Fig. 22. The fish seen from below. Drawing; natural size, al, anterior lateral radiating 

 organs ; ma, mandibular radiating organs ; ml, mediolateral radiating organs ; 

 op, opercular radiating organs ; pe, pectoral radiating organs ; pi, posterior 

 lateral radiating organs ; va, anterior ventroanal radiating organs; vc, ventro- 

 caudal radiating organs ; ve, ventromedial radiating organs ; vp, posterior 

 ventroanal radiating organs. 



Fig. 23. Axial section vertical to the median plane of the fish through a posterior lateral 

 radiating organ. Stained: haematoxylin-picric aciil-fuchsin. Drawing; magni- 

 fied 1 : 140. b, blood vessels ; c, connective tissue of the interior of the organ ; 

 p, section through the outer horseshoe-shaped pigment cell band ; pc, radiating 

 cells; pp, internal pigment cell layer; si, scale underlying the radiating organ; 

 ss, scale covering the radiating organ ; t, section through the H-shaped thicken- 

 ing of the coverino- scale. 



