FIG. 35. Transverse section through anterior part of head of a double 

 monster belonging to Class I., the type illustrated in PI. I. figs. 4 and 5. 

 The posterior walls of the adjacent eyes are just grazed by the section, and 

 several of the ocular nerves and muscles are seen. The cerebral lobes and 

 their cavity, the pineal sacs, and a forwardly projecting part of the com- 

 posite optic lobes come into the section. Noticeable in the middle line, 

 ventrally, is a large cartilage consisting of the fused adjacent hyomandi- 

 bulars, with which articulates a small bar representing the adjacent 

 Meckelian cartilages. Compare with PL III. fig. 13 (normal) and with 

 PI. XIII. fig. 48 (union at medulla). Pis. X.-XI1. figs. 39-46 are also from 

 sections of a double monster similar to this one, i.e. with union at optic 

 lobes. For plane of section see PI. XXI. figs. 88-90. Other references are 

 given under PI. I. fig. 4. (x2o. ) 



FIG. 36. Transverse section from same series as Fig. 35, but passing 

 across the middle of the outer eyes. There are two infundibula, but the 

 composite optic lobe region has a single cavity. The trabeculae cianii are 

 doubled. A few of the muscles belonging to the adjacent eyes are cut across 

 near their origins. In the floor of the mouth, the two first visceral arch 

 bars and the copula of the third are seen. Compare with PI. III. figs. 14 

 and 15 (normal). For other references see under PI. I. fig. 4, and for plane 

 of section see PI. XXI. figs. 88-90, line 36. (xao.) 





PL. VIII. 



