386 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



first; 10, the twenty-eighth ; 11, the thirty-third ; 12, the thirty-fifth ; 13, the thirty- 

 eighth, and 14, the fiftieth. 



In the second series Fig. 15 is the sixth section ; 16, the ninth ; 17, the twelfth ; 

 18, the twentieth ; 19, the thirty-first ; 20, the thirty-sixth ; 21, the forty-third ; 22, the 

 forty-sixth ; 23, the forty-ninth, and 24, the fifty-second. 



Figure 25, the sections of Salpa africana which are shown on a smaller scale at 1, 

 2 and 3 of cut Y on page 107. 



Figure 26, the section of Salpa africana which is shown on a smaller scale at 4 in 

 cut Y on page 107. 



PLATE XXXVIII. 

 SALPA PINNATA. 



Two aggregated salpae, a right-hand and a left-hand one, at the stage which is 

 shown in Plate VIII, Fig. 1. 



PLATES XXXIX AND XL. 

 SALPA CYLINDRICA. 



These sections are from a stolon of Salpa cylindrica at the stage shown in Plate 

 VIII, Fig. 2. 



The figures are placed with their proximal surface below, like the plates of Salpa 

 pinnata, but the first one in the series, Fig. 1, instead of being at the lower left-hand 

 corner, is at the upper right-hand corner. The series included nearly two hundred 

 sections, and those which were drawn were selected for the purpose of giving a con- 

 secutive series in as small a number of figures as possible, and while the right-hand 

 ones are not cut in exactly the same plane as the left-hand ones, the difference is not 

 very great, and its nature is easily understood from Plate VIII, Fig. 2. With this 

 slight difference the following series gives what is in effect a more complete series 

 from a single salpa : 



Fig. 1, right. Fig. 2, right. Fig. 3, right. Fig. 4, right. Fig. 5, right. Fig. 6, 

 right. Fig. 7, right. Fig. 1, left. Fig. 2, left. Fig. 3, left. Fig. 4, left. Fig. 5, 

 left. Fig. 6, left. Fig. 7, left. Fig. 11 and Fig. 12, left. Fig. 13, left. Fig. 14, left. 

 Fig. 19, right. Fig. 20, right. Fig. 21, right. Fig. 17, left. Fig. 18, left. Fig. 19, 

 left. Fig. 20, left. Fig. 21, left. Figs. 21 and 22. 



PLATE XLI. 



Figure 1, embryo of Salpa pinnata at about the same stage as Plate XIV, Fig. 2. 

 25, cavity of amnion. 23, supporting ring of placenta. 24, blood bud. y', body 

 cavity of chain-salpa. y", blood space of placenta. 



Figure 2, embryo of Salpa pinnata a little older than Plate XVIII. </'", cloaca. 

 <7 V , place where cloacal aperture is formed at a later stage. /, pericardium, c, pha- 

 rynx, s, ganglion, v, cellulose, z, mouth. //", blood space of placenta. 21, outer, 

 22, inner fold of amnion. 23, supporting ring. 24, blood bud. x is place of stolon. 

 k, of eleoblast. 



Figure 3, embryo of Salpa pinnata a little older than in Plate XXXV, with the 

 stolon in the stage shown in Plate XX. g'" , cloaca. g v , cloacal aperture, k, eleo- 

 blast. o, gill, p, intestine, p", placenta at stolon, z, mouth. 



Figure 4, stolon of Fig. 3 more highly magnified, d', digestive tube of stolon. 

 a, ectoderm, a', ectoderm of stolon, n, germinal mass. 



Figure 5, embryo of Salpa pinnata with stolon in stage shown in Plate XXI. 

 Reference letters as in Fig. 3. 



Figure 6, stolon of Fig. 5 more highly magnified. 



