BOSACEUS, LIXCK (COMATULA EOSACEA OE LAMAECK). 
543 
Fig. 4. A group of parent cells containing vesicles of evolution, and forming a portion of 
the tissue of the testis, X 40 linear. 
Fig. 5, a-e. Parent cells with vesicles of evolution in various stages of development, 
X40 linear. 
Fig. 6, a-c. Mature vesicles of evolution containing spermatozoa, X 80 linear. 
Fig. 7. Spermatozoa, X 120 linear. 
Fig. 8. Egg shortly after impregnation, X 40 linear. 
Figs. 9-13. The process of yelk segmentation, x40 linear. 
Fig. 14, a-c. Further enlarged views of the earlier stages of yelk segmentation, showing 
three groups of the “ direction vesicles,” X 80 linear. 
PLATE XXIV. 
Figs. 1-4. The development of the pseudembryo within the vitelline membrane, X 40 
linear. In this case the development is somewhat abnormal. 
Fig. 5. Dorsal aspect of the pseudembryo shortly after the rupture of the vitelline sac, 
X 40 linear. 
Fig. 6. Dorsal view of the pseudembryo a little more advanced, X.40 linear. 
Fig. 7. Ventral aspect of the pseudembryo a little later, showing the pseudostome and 
pseudoproct, and the rudiments of the cup plates of the embryo, X 40 linear. 
Figs. 8, 9, 10. Ventral, dorsal, and lateral aspects of the pseudembryo shortly before the 
disappearance of the ciliated bands, X 40 linear. 
PLATE XXV. 
Figs. 1-3. The pseudembryo losing its special organs of assimilation and locomotion and 
passing into the “ pentacrinoid stage,” X40 linear. 
PLATE XXVI. 
Fig. 1. Pentacrinoid larva immediately after the complete separation of the oral valves, 
expanded, X 40 linear. 
Fig. 2. Pentacrinoid in the same stage, the cup closed, x40 linear, but afterwards 
slightly reduced to suit the size of the plate. 
Fig. 3. A portion of the oral disk of the same stage seen from above, in a state of com- 
plete expansion : a, patent oral aperture bounded by a ring of contractile tissue, 
and showing yellow richly ciliated granular folds, arranged somewhat spirally 
on the walls of the digestive cavity; b, central ring of the radial vascular 
system ; c, non-extensile tentacles in immediate connexion with the vascular 
