ANTHOPHYSA ROSEA. 299 



tions (Plate 23, fig. 1), is divided morphologically into two portions, upper and 

 lower. The latter, the "infundibulum," of Chun, is reduced to a thin layer, 

 composed of two series of tile-shaped cells, ectodermic and entodermic. In 

 its extent it closely follows the outline of the lower portion of the pneumatocodon. 

 It is evident that Bedot was correct in his statement that there is no trace of a 

 typical stem in Anthophysa. The upper portion of the pneumatosaccus has 

 not been described in detail. Its most striking feature is that its cavity, above 

 the thin "infundibulum," is completely lined by a very thick ectoderm layer 

 composed of several rows of polygonal cells which here and there enclose irregu- 

 lar spaces containing remnants of "giant cells." Chun could trace this laj'er 

 over only about "zwei Drittel der Innenflache der Luftflasche" ('97b, p. 63), 

 but as his specimen was in poor condition, it is doubtful whether his account 

 reproduces a condition normal for the Atlantic form. Near the apical pole 

 the layer in question is separated from the entoderm of the pneumatosaccus 

 only by the "stutzlamella." At a lower level, however, (Plate 23, fig. 2), a 

 third cell layer, one cell thick, lying between the stutzlamella, and the lining 

 tissue, and separated from the latter by several much torn gelatinous or chitin- 

 ous strands, can be seen. The relationships of these various layers can best be 

 worked out on longitudinal sections at the zone of transition between the upper 

 thick-walled, and lower thin-walled portions of the pneumatosaccus. Commenc- 

 ing below, we find that the latter is composed of flat tile-shaped cells. Over 

 most of it the two layers, entoderm and ectoderm, are in contact with each other. 

 But just below the critical region the stutzlamella is to be seen. Slightly 

 above this level the ectoderm becomes thicker, and as we pass upward, it divides 

 into two layers between which a second stutzlamella, described by Chun 

 ('97b, p. 62), as a "Chitin ring," appears. Here all three cell layers are one 

 cell thick, but immediately above this point the lining ectoderm becomes several 

 cells deep. The outer layer of ectoderm, on the other hand, remains one cell 

 thick; but its cells become more columnar, and it is thrown into several folds 

 (Plate 23, fig. 2). The outer ectoderm layer can be traced from this point upward 

 about one half the distance to the apex, beyond which point it loses its character 

 as a continuous layer, being represented only by scattered and very much flat- 

 tened cells. Near the upper pole of the pneumatosaccus no trace of it is found 

 (Plate 21, fig. 4). The stutzlamella which separates the two layers of ectoderm 

 entirely encloses the hning layer, and, probably owing to preservation, it is much 

 torn at the apex. Where the outer ectoderm is absent, the stutzlamella is 

 in immediate contact with the much denser supporting layer which primarily 

 separated ectoderm from entoderm. 



