PLATE XXVII . 



Figs, i to 5. Ascidia ad/tcErcjis. 



I and 2 are habit sketches, i showing particularly the way in which the 

 animals aggregate together to form a continuous flattened layer. The 

 position of the atrial siphon somewhat on the upper surface is shown. 

 Natural size. 



3. Left side of animal, dissected from the test. 



4. Portion of peripharyngeal field showing a portion of the tenacles. the 

 hypophysis inouth, the gland-ganglion mass, .?. 5., and the dorsal lamina, 

 d. /., with its few, simple marginal teeth. 



5. Small portion of branchial sac drawn with special reference to the irreg- 

 ularity in distribution of the intermediate papillae,^, i.; i. e., their pres- 

 ence or absence in the intervals between the transverse vessels. 



Figs. 6 to 9. Molgula graph ica. 



6. Habit sketch, seen from right side. Enlarged 2 times. 



7. Left side of animal, dissected from test. 



8. Portion of peripharyngeal field; s.s., the gland ganglion mass. 



9. One of the much branched tentacles. The extent of the branching, and 

 the rolling up of the ultimate branches is even more pronounced in the 

 specimen than is here shown. 



Figs. 20 and 21. Styela yahutatensis. Natural size. 



Figs. 22 and 23. Styela tnmcata. Natural size. Fig. 22 suggests the aggrega- 

 tion of the individuals and 23 shows the general conical form and the 

 truncation of the basal end. 



(260) 



