PLATE X. 
Fig. 1. 
Fig. 2. 
Fig. 
Fig. 4 
Fig. 5 
Fig. 6 
Colella thomsoni, n. sp. . 
Colony of Colella thomsoni; natural size. 
Upper end of colony of Colella thomsoni ; natural size. 
Peduncle and lower end of head of Colella thomsoni ; natural size. 
Surface view of upper end of head of Colella thomsoni ; natural size. 
Transverse section through head of Colella thomsoni ; natural size. 
Dissection of head of Colella thomsoni, to show arrangement of Ascidiozooids ; 
natural size. 
Fig. 7. Vertical section of lower part of head and upper part of peduncle ; natural 
size. 
Fig. 8. 
Fig. 9. 
Fig. 10. 
Part of the surface of the head ; enlarged. 
An Ascidiozooid dissected out from the head of Colella thomsoni; natural size. 
The Ascidiozooid of Colella thomsoni, seen from the left hand side ; magnified 
(S., 1 inch). 
