16 G. HERBERT FOWLER. 



Fig. 8. Diagram of the various forms and conditions of the mesen- 

 teries in a polyp of Type A. Those numbered 1, 3, 5, 8, 

 10, 12 are unmodified and normal. The others, 2, 4, 6, 7, 

 9, 11, are modified in all the polyps of this type; they 

 are from camera lucida drawings of the same mesentery at 

 different heights. The arrows and Eoman numerals in 

 Fig. 6 show the planes in which the successive sections are 

 taken ; 2 shows the endodermal swelling, and the upper 

 opening of the canal ; 6 shows the lower opening ; 9 is 

 below the stomatodEeum, and bears a filament ; and in 1 1 

 no trace of the modification remains, the mesentery being 

 normal, and similar to those of Type B. 



Fig. 9. Transverse section of a modified mesentery, passing through 

 both arms of the canal. 



Fig. 10. Transverse section of the corallum of a branch of M. aspera. 



