384 WILSON. 



EXPLANATION OF PLATE XIV. 

 {Esperella Jibrcxiiis.) 



Fig. I. Esperella fibrexilis. x i^. 



Fig. 2. Vertical section of Esperella, showing canal system and skeleton. A. 4. 



Fig. 3. Spicules, a, oxytylote ; b, modification of the same ; c, after treatment 

 with caustic potash ; d, toxaspire ; e, sigma ; /, sigmaspire. D.4. 



Fig. 3'. a, i, c, views of small shovels : a, somewhat from the end ; b, face 

 view ; c, side ^iew. d, a small sigma which will develop into a shovel. X 900. 



Fig. 3". Large shovels — a, face ^dew ; b, side view; d.l. dorsal lobe; v.l., 

 ventral lobe ; l.n. lateral notch ; /., tooth. X 900. 



Fig. 4. Dermal membrane. A. 4. 



Fig. 5. Surface of adult. 4-inch objective. 



Fig. 6. Ditto, showing osculum and oscular cavity. 



Fig. 7. Surface of adult. 4-inch objective. 



Fig. 8. .Section : gemmules in mesoderm of parent. X 800. 



Fig. 8'. Different conditions of the nucleus in the gemmule cells. ■ 



