266 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
of Apteryx. The notochord seems to arise from the thick sheet of meso- 
blast which grows forward from the primitive streak. In the embryo, just 
before hatching, each of the four large cutting teeth present in the front 
of the jaws in the adult is represented by three small teeth, which must 
fuse together later. No vomerine teeth were observed. The coloration 
of the embryo is very different from that of the adult, and in the course 
of the development the following stages seem to be passed through : — 
(1) longitudinal stripes, (2) transverse bands, and (3) spots. In general 
the development of the coloration seems to be in harmony with Eimer’s 
conclusions. 
Prof. Schauinsland * publishes some brief notes of his observations 
on this subject. The sub-germinal cavity is very large, and is filled in 
life with an almost liquid mass which coagulates during preservation. 
The chorda, mesoblast, and entoblast arise exactly as described by 
Mitsukuri for Chelonians. The neurenteric canal remains open for a 
long time. Prof. Schauinsland also noticed the differences between 
the coloration of the embryo and of the adult described by Prof. Dendy. 
He promises an illustrated account of the development later. 
Development of Ringed Snake.f — Prof. Ludwig Will has investi- 
gated the earlier stages of development of Tropidonotus natrix , with 
the view of reconciling the contradictions which exist in the litera- 
ture of the subject as to the relations of archenteron and neurenteric 
canal. By Kupffer, a neurenteric canal was described in snake embryos 
at a very early stage ; while Hoffmann, on the other hand, found that it 
did not appear till late in development. Dr. Will showed several years 
ago that in the Gecko ( Platydactylus ) the neurenteric canal has an inter- 
mittent existence, and he suspected that this might also be the case in 
snakes. His results justify this surmise. The archenteron in Tropi- 
donotus is of small size, and is apparently diminishing, for there is 
much variation among the embryos in this respect. On account of the 
small size of the primitive gut, its opening is much less conspicuous 
than in other reptiles. The opening is formed either by the gradual 
widening of a single split or by the fusion of several small chink-like 
openings. The opening so formed puts the archenteron in communica- 
tion with the segmentation cavity, and, by means of the invagination 
cavity, with the exterior ; it constitutes Kupffer’s canal. But this canal 
does not persist, and is obliterated before the medullary groove closes ; 
later, at the stage when a large number of primitive segments have 
appeared, it is reformed and constitutes the neurenteric canal. In the 
reduction of the archenteron, and in certain peculiarities in the formation 
of endoderm and mesoderm, the author believes that snakes approach 
birds and mammals more nearly than other reptiles. 
Development of the Teeth in Diprotodont Marsupials.;]; — Albertina 
Oarlsson has investigated the development of the dentition in two species 
of Petaurus, two species of Trichosurus, and Tar sipes rostratus. It is 
necessary to recall the current interpretations. 
According to Leche, there are in marsupials three generations of 
teeth : — (a) An anterior prelacteal set which does not cut the gum ; 
* SB. Akad. Wiss. Berlin, xl. (1898) pp. 629-31. f Tom. cit., pp. 609-18. 
x Zool. Jahrb. (Abth. Anat.), xii. (1899) pp. 407-24 (1 pi.). 
