EXPLANATION OF PLATES. 385 



PLATES XXXII AXI> XXXIII. 



A series of sections transverse to the long axis of the bodies of six aggregated 

 salpae of Salpa pinnata, at the stages which are shown in Plate VI, Figs. 2, 3 and 4, 

 and Plate VII, Figs. 1 and 2. The structure which is colored blue in Plate XXXII, 

 Figs, (i and 7. K and Fig. I, M, is the intestine, and the structure marked <j in Figs. I, 

 .!/ : ">. .!/ ; 7, K and 8, K, is the oesophagus. 



PLATE XXXIV. 

 SALPA PINNATA. 



Figure 1, a transverse section near the root of a stolon from a mature salpa which 

 has produced great numbers of buds. 



Figure 2, the genital rod, more enlarged. 



Figure 3, the region of the right perithoracic tube, more enlarged. 



Figure 4, a horizontal longitudinal section through the genital rod of the same 

 stolon, a little farther from the root. 



Figure 5 and Fig. 0, two sections through the endodermal tube and the right 

 perithoracic tube of the same stolon. 



Figure 7, a section above the level of the perithoracic tube. 



Figures 8, !>, 10 and 11, sections through the perithoracic tubes of more advanced 

 stages, to show the way in which the perithoracic tubes and the endodermal tube are 

 cut by the folds of ectoderm. 



PLATE XXXV. 



Median longitudinal section through an embryo of Salpa pinnata, about the stage 

 shown in Plate XLI, Fig. 3. 



a, ectoderm, a', ectoderm of stolon, b, endoderm. c, pharynx, d', endodermal 

 tube of stolon, e, heart. /, pericardium. </'", cloaca, cf, cloacal aperture, k, eleo- 

 blast. n, germinal jnass of stolon, o, gill, p, intestine, p', stomach, p", anus. 

 s, ganglion, t, ciliated funnel, v, cellulose mantle, w, oral muscles, y', blood 

 spaces of amnion. //", blood spaces of placenta, z, mouth. 



10, roof of placenta. 15, body cavity. 21, outer fold of amnion. 22, inner fold 

 of amnion. 23, supporting ring of placenta. 



PLATE XXXVI. 

 SALPA PINNATA. 



Transverse sections through two aggregated salp;o, a right-hand and a left-hand 

 one, at the stage which is shown in Plate VII, Fig. 3. 



Figure 1 is the third section in the series ; 2 is the fifth ; 3 is the seventh ; 4, the 

 tenth ; 5, the eleventh ; (i, the thirteenth : 7, the sixteenth ; 8, the twentieth ; !, the 

 twenty-third; 10, the twenty-seventh ; 11, the thirtieth; 12, the thirty-second : 13, 

 the thirty-fourth : 14, the thirty-eighth ; 15, the forty-third, and 16, the forty -eighth. 



PLATE XXXVII. 

 1-24, SALPA PINNATA. 25 AND 26, SALPA AFRICAN \. 



Figures 1-14 are transverse sections through two aggregated salp;r, at the stage 

 which is shown in Plate VII, Fig. 4. 



Figures 15-24 are at the stage which is shown in Plate VII. Fig. a. 



In the first series Fig. 1 is the first section : Fig. 2, the second ; 3, the third ; 4. the 

 fifth : ."). the sixth : G, the seventh : 7, the eighth : 8, the eleventh : 9, the twenty- 



