- Horizontal !ouble monster (union 



illustrated in V\. I. figs. ; X. figs. 35-38, and Pis. X., XI. figs. 



iis, however, sonic iuipoitant differences when compared with the two l.< 

 one another, so that the common lens lies buried below the surface in th': 



greater evidence of duii! i > do the parts round th< ,, -fourth vc;, ng to 



the body is cut through >s in Ms. X., XI. figs. , hows a dou! . of th 



other structures. The '. rest of the alimentary < njle, but there are two swim-t>! 



general references see tin ;. 4. 



e type as the sp.-< 



e adjacent eyes and brain 



ret. The ey' 



e optic lobes show 

 ^^^Hfe'OI the specimen, 

 1 of certain 

 der r : 



United inner supraorbitals 



Outer supraorbital 



Cavity of cerebral lobes 



An outer eye 



Ventricle III 



Outer supraorbital 



Optic lobes 



Periotic cartilage 



Ventricle IV 



Parts of labyrinth 

 Medulla 



United haemal arch cartilages 



Mesial muscular mass- 



Composite spinal cord--"" 



United inner supraorbitals 

 Outer supraorbilal 

 Cavity of cerebral lobes 

 Rectus oc. int. 



Ventricle III 

 Optic lobes 



Periotic cartilage 

 Ventricle IV 

 Parts of labyrinth 



Medulla 



' Parachordals 



The two notochords 



Mesial muscular mass 



Outer series of muscle segments 



FIG. 43. Horizontal section of the embryo described above, 

 passing through upper parts of eyes, brain and auditory organs. 

 The fused adjacent sides of the optic lobes form a rounded 

 mass, projecting into the central cavity. Dorsally, the sagittal 

 planes of the twin fore-brains are much inclined towards one 

 another. (xi4.) 



FIG. 44. Horizontal section of the embryo described above, 

 passing through the middle of the outer eyes and of the 

 auditory organs. The mesial optic lobe mass, referred to 

 under Fig. 43, is now larger. The mesi.il muscular mass 

 between the two notochords is also to be noted. ( x 14.) 



Composite spinal cord 



Inner olfactory organs 



Olfactory cartilage 



United inner eyes and lens 



An outer eye ... 

 Rectus oc. sup. 



Rectus oc. ext. .. 

 The two infundibula and .."' 

 their outgrowths 



Hyomandibular 



Upper parts of gill arches . 



The two notochords I. 



and their parachordals - - 



Oesophagus 

 teginning of the two air ducts 



Head-kidney . 



The two notochords ni'Z< 



The composite spinal cord 



Inner olfactory organs 

 Olfactory cartilage 



Obliquus oc. inf. 



Rectus oc. sup. 



Optic nerve 



Rectus oc. ext. 



The two infundibula and 



their outgrowths 

 Hyomandibular 

 The two notochords and 



their parachordals 

 Upper parts of gill arches 



Beginning of body cavity 



Beginning of stomach 

 Part of liver 



Lateral muscles 



Mesial muscular mns^ 

 The two notochords 



The composite spinal cord 



FIG. 45. Horizontal section of the emb 



v.-: ihnn in the last two tigr 

 two adjacent c> 



seen, as also arc the two 



fundibulai imiHpmlh and the origins of the two swim- 

 bladders. ( 



t.il section < 



, - , -,:i Fig. 45. 



v ':> is cut in me*i 



id pb 

 nerves. ( x 14. ) 



]. F. G. 



PI, XII. 



XII 



