254 JOHNS HOPKINS UNIVEESITY MORPHOLOGICAL MONOGRAPHS. 



species takes no part in the formation of the embryo, and is very transi- 

 tory, this difference is only a superficial one, and it leads to no complica- 

 tions, nor does it in any way affect the comparison between the embryos 

 of different species. 



The brood chamber, Brutsack, of Salpa democratica in Salensky's 

 first paper (2), is obviously the cavity of the follicle which is designated in 

 my figures of Salpa hexagona, Plate X, by 5. It is the cavity which he 

 calls, in his second paper (5), in all the species except Salpa democratica, 

 the cavity of the follicle, and designates by the letters Fh, as in his 

 Taf . 10, Fig. 9, pin for example. It is true that its walls are formed, in 

 great part at least, from the cells of the duct rather than from those of 

 the egg capsule,. but his figure of the embryo of Salpa pinnata (5), Taf. 10, 

 Fig. 9, shows clearly that this is not a fundamental difference, for in the 

 latter species his figures show that the cells of the egg capsule and those 

 of the duct are parts of a continuous layer of follicular epithelium with- 

 out any sharp line of separation. I must not be held to deny the 

 existence of the difference between the two species in this particular, 

 since I simply wish to point out that, while real and interesting, it has 

 no deep significance and does not involve any fundamental difference 

 between the two embryos. 



The inner lamella of the brood chamber of Salpa democratica, Brs, a, 

 is simply the somatic layer of the follicle, designated in my Plate X and 

 in other plates by 7. It is the layer which, in his second paper, he has 

 designated in other species by the letters Fe. 



The outer lamella of the brood chamber, Brs, (3, is, as he points out 

 on page 378 of his second paper, the structure which I have called the 

 epithelial capsule, 6', and that which he calls, in his second paper, the 

 Epithelialhugel, Eph. The part of the follicle which in his first paper 

 he designates by the letter p, and which, as he shows, forms the greater 

 part of the placenta, is exactly the same as that part of the somatic, layer 

 of the follicle which in other species forms the roof of the placenta and 

 is designated in this memoir by 10. His figures of the embryo of Salpa 

 democratica in his second paper, especially Taf. 27, Fig. 3, dl, show that 

 the sides of the placenta are strengthened by a supporting ring, Eph, 

 derived from the lower part of the epithelial capsule exactly as in the 

 species which I have studied. 



In his second paper (5), p. 378, he himself points out these facts, and 

 his retention of one terminology for Salpa democratica, while another is 

 used for the other species, unfortunately helps to impress the reader 

 with an exaggerated notion of the difference between the species. 



