756 B. W. KUNKEL 



SUMMARY 



The principal points which I would emphasize in conclusion 

 are as follows: 



1. The chondrocranium of Emys resembles^ closely that of 

 Dermochelys and Chelone and, in general features, is similar to 

 that of Lacerta, but is of heavier construction. 



2. The planum basale is parachordal in position, surrounding 

 the chorda dorsalis on all sides. 



3. The condylus occipitalis is annular in form, a central con- 

 cavity being present around the chorda dorsalis. 



4. The arcus occipitales do not reach the tectum posterius 

 distally so that the foramen occipitale magnum is not separated 

 completely from the fissura metotica. 



5. There are three foramina spino-occipitalia present at the 

 stage modelled, the two anterior of which fuse later. 



6. The tectum posterius is strongly developed, exhibiting a 

 processus ascendens of large size and a stout processus posterior 

 which limits the foramen occipitale magnum dorsally. 



7. The fissura metotica becomes wide at its antero-ventral 

 end at which point the nervns vagus and vena jugularis leave 

 the cranial cavity. 



8. The planum basale projects laterally beyond the lateral 

 portions of the occipital region as the crista inferior which thereby 

 forms the ventral side of the sulcus supracristularis. 



9. The fenestra cochleae opens into the sulcus supracristularis 

 at its anterior end (recessus scalae tympani) immediately in 

 front of the fissura metotica. 



10. The fenestra cochleae is the posterior opening of the canalis 

 perilymphaticus which has a horizontal direction and opens into 

 the cavum cochleae on the median wall of the latter. 



11. A canalis hypoperilymphaticus is found in embryos older 

 than that modelled; passing parallel and ventral to the canalis 

 perilymphaticus and communicating between the recessus scalae 

 tympani posteriorly and the cavum cochleae anteriorly. It con- 

 tains nothing but loose connective tissue. It develops anteriorly 

 irom its posterior end. 



