PLATE 9. 



Fig. 1-8. DOLABBLLA AGASSIZI, Sp. nov. 



Fig. 1. Single palatal spine, detached from the epithelium, but still imbedded in the common 

 cuticula of the palatal flap. X 170. 



Fig. 2. Early stage in the formation of a palatal spine. The spine here appears as a slightly 

 thickened cap on the distal end of the granular basal cell. The thick common cuticula overUes all the 

 epithelial cells of the figure, but is not here represented. X 175. 



Fig. 3. Base of palatal spine, showing its relation to the basal matrix-cell, and to the general 

 columnar epithelium. Part of another basal cell is shown at the left, its spine not being visible in 

 the section. X 175. 



Fig. 4. A later stage than that shown in the preceding figure, two layers of the young spine having 

 been formed. X 175. 



Fig. 5. A still later stage of the same, the section passing to one side of the nucleus of the basal 

 matrix-cell. X 175. 



Fig. 6. Later stage of the same process. The spine and basal cell have both increased in size. 

 The cytoplasm of the matrix-cell contains numerous irregular vacuoles and is coarsely granular. X 175. 



Fig. 7. Section across the long axis of the palatal fold as seen under low magnification; a, dorsal 

 surface, forming part of the floor of the pharyngeal duct. The one-layered columnar epithelium c, 

 bears a sUght cuticula on the dorsal side, o, which thickens greatly on the ventral surface, b, and 

 contains the palatal spines, differentiated in its substance, and resting upon the epithelium, or raised 

 above it, and projecting freely; c, the free margin of the palatal fold; d, section of a saUvary duct. 

 X 18. . 



Fig. 8. Detail of fully formed palatal sjiine showing its relation to the epitheUum and to the 

 common thick striated cuticula, c, to the siu'face of wluch it does not yet extend, being still in contact 

 with its matrLx-cell, b. X 220. 



