PLATE 20. 



Alcxandromenia agassizi. X 25. 



Figs. 1, 2, 4, 9 correspond to lines A, D, B, C of fig. 3, pi. 7 (anterior end). 



Fig. 3, 5, 7, 8, are along linos F, G, H, E, of fig. 5, pi. 7 (posterior end). Fig. 7, X 20. 



Fig. 6. Cross section of heart at junction of its two divisions. 



