ILLUSTRATIONS. 93 



PLATE XXIV. 



(All figures of Notocrinus virUis.) 



Fig. 1. Fully formed larva, in ventral aspect. X28. 



Fig. 2. Lar\'a, mounted in balsam so as to sliow the skeleton. In the posterior end are seen the glandular 

 sacs. One supplementary plate is seen besides the primary terminal stem-plate. Dorsal 

 view. X55. 

 Fio. 3. Side view of a larva with a process apparently coalesced with the marsupial wall. Four supple- 

 mentary terminal plates are seen. The glandular sacs were not distinct in this specimen. X55. 

 FiQS. 4, 5, G. From a series of sagittal, longitudinal sections of the larva. 



Figure 4. A nearly median section, showing the anterior prolongation of the parietal canal. 



Figure 5. A somewhat more lateral section in which is seen the hydroca'l. 



Figure 6. A still more lateral section, showing a downward prolongation from the parietal canal : 



the closed pore canal. 

 The indentation in the anterior end of the two first of these figures is the suctorial disk. In figure 6 

 the anterior part has been sUghtly restored. There are thirty-five sections between figures 

 4 and 5, eighteen sections between figures 5 and 6. X80. 

 Figs. 7, 8, 9. From a series of frontal, longitudinal sections of the larva. Figure 7 the more dorsal, figure 9 

 the more ventral of the sections. 

 Figure 7 shows four glandular sacs in section. 



Figure 8 shows part of the anterior prolongation of the parietal canal. 



Figure 9 shows the hydrocccl and the downward prolongation from the parietal canal representing 



the closed pore canal. The small accumulation of cells, marked ** in the anterior part Ls part 



of the anterior prolongation of the parietal canal. The Uttle space between the two parts of 



the hydrocoel is part of the oral (left) coelom and is seen to unite with it a few sections farther on. 



There are 28 sections between figures 7 and 8, 10 sections between figures 8 and 9. X80. 



PLATE XXV. 



(All figures of Nolocrintis virilis.) 



Figs. 1, 2, 3, 4, 5, 6. From a series of transverse sections of a larva, figure 1 being the anterior of them. 

 (A continuation of the series is given in plates xxvi, figures I to 3.) X70. 



Figures 1 and 2 are from the part above the vestibulary invagination, through the region of the 

 suctorial disk, which is indicated by the double indentation. In the middle is seen, below the 

 thick ectoderm, the nervous system, undivided, almost ganglion-like in figure 1, branching 

 in figure 2. A Uttle inside the nervous system is seen the section of the narrow anterior pro- 

 longation of the parietal canal, and nearer the middle is seen the chambered organ. 



Figure 3 is from the anterior part of the vestibulary invagination; the nerves have dis- 

 appeared, but in the interior are seen, as in the foregoing sections, the parietal canal and the 

 chambered organ. 



Figure 4 shows the origin of the pore canal from the parietal canal. The small space seen between 

 this and the dorsal coelom is an anterior prolongation from the oral coelom. The dorsal coelom 

 is divided in the middle by the vertical mesenterj'. 



Figure 5 is from the region of the hydrocoel. On the left side of the hydrocoel is seen the anterior 

 prolongation of the oral coelom; the space on the right side of the hydrocoel is the parietal canal; 

 the dorsal coelom is an undivided space covering the whole dorsal side. In the skin to the left 

 of the hydrocoel are seen two small spaces, the minor of them being the pore canal, the larger 

 a glandular sac. 



In figure 6 the oral coelom has also appeared to the right of the hydrocoel. 



There are two sections between figures 1 and 2, about si.vty between figures 2 and 3, about thirty 

 between figures 3 and 4, seven between figures 4 and 5, and sixteen between figures 5 and 6. 

 Fia. 7. Part of a section showing 3 glandular sacs. X290. 



FiQ. 8. Part of a transverse section, in a sUghtly younger stage than that from which the series of transverse 

 sections have been figured, the vestibulary invagination being represented by only a sUght 

 concavity. In the figure is seen an evagination from the oral coelom, which appears to represent 

 a glandular sac in formation. The small ring seen outside the ccelom is the pore canal in section. 

 It is closed also in this specimen. X 105. 



PLATE XXVL 



(All figures of Notocrinus virUia.) 



Figs. 1, 2, 3. Continuation of the series of sections represented in figures 1 to 6, plate xxv. 



P'igure 1 shows the beginning formation of the primary tentacles from the hydrocoel. The oral 



calom is still divided in two lobes, one on each side of the hydrocoel. 

 Figure 2 is from the region below the vestibulary invagination, also below the hydrocoel. The 



oral coelom now occupies the whole of the ventral side. Two glandular sacs are seen in either 



side of the larva. 



