450 



B. RAY LANKESTER AND ARTHUR WILLEY. 



with the body-cavity, and consequently calls it " Leibcshohle/' 



or coelom. 



Fig. 4. 



Copy of llolph's theoretical section through an older larva, showing the com- 

 mencing longitudinal downgrowths. E. Epidermis. Ey Visceral epi- 

 thelium of the (future) atrial cavity. E^. Parietal epithelium of same. 

 U. Subcutaneous tissue. Other letters as in Fig. 3. 



Fig. 5. 



Copy of Rolph's theoretical section, showing the meeting together of the 

 "epipleura" in the ventral middle line. A. Atrium. R. Raphe. 

 Other letters as in Figs. 3 and 4. 



