POLYEMBRYONIC DEVELOPMENT IN TATUSIA 639 
Furthermore, it was observed in at least three living specimens, so 
that there can be no doubt but that during the early history 
of the embryonic buds, Nos. II and IV are more highly devel- 
oped than their mates I and III. And what else can this mean 
than that phylogenetically the former pair should precede the 
latter. 
This obvious difference in size does not last indefinitely, and 
indeed is no longer discernable after the embryonic rudiments 
have become slipper-shaped (fig. 5). 
That primary buds may also be precursors of secondary buds 
in Mulita is, I believe, to be inferred from the work of Fernandez 
(09) on that form. Unfortunately, he has but a few scattered 
stages at his command, and therefore was not able to give us a 
full history of the development of the embryonic rudiments. 
His specimen 46, which is the one next to his youngest stage 
(corresponding to Specimen 233), already has embryonic rudi- 
ments fully as well developed as those in Specimen No. 226 (plate 
11). Nevertheless, in speaking of the relation which exists be- 
tween the ectoderm of the common amnion and that of the 
embryonic diverticula in this specimen, he makes the following 
significant statement, ‘‘ Der Cervix uteri zu, d.h. tiber dem Anfang 
der Medullarplatte, ist das Amnion keines Tieres geschlossen, as 
steht vielmehr durch eine sehr weite Offnung mit dem Amnion 
eines oder mehrerer Nachbartiere in vollkommener Kommunika- 
tion.’”!2, Again in the same paragraph he says, ‘‘ Das Amnion eines 
Einzelembryo kann sich auch direkt in diese Blase 6ffnen, ohne 
vorher mit den Amnia andrer Embryonen in Verbindung getreten 
zu sein.”’ 
If we pass from these two statements to an examination of his 
figures 1 and 2 (plate 17), which are photographs of vesicles show- 
ing well-formed embryos, we shall find further evidence of this 
same nature. The specimen shown in figure i is from a vesicle 
containing 11 embryos, six of which appear in the photograph. 
On account of the advanced stage of development, the evidence 
that two embryos have come from a common diverticulum must 
be sought in the relation of the amniotic canals to the common 
2 Loe. Gite, pola. 
