1892,] Embryology. 1047 
separate from one another, after their number is increased, to leave the 
lumen of the digestive tract. Only short stomodeal and anal invagi- 
nations arise from the ectoblast. 
As the mouth forms, ectoblastic cells around it sink in to form the 
nervous system. The reproductive organs are recognizable before this, 
as two large cells, one in each of the rows of only five or six mesoblast 
cells. 
In the main the paper confirms the observations of Gitte upon 
Note on an Abnormal Polygordius Larva.—Since reading 
Mr. E. A. Andrews’ article on Bifurcated Annelids in the September 
number of this journal, it has seemed to me that some notes and 
sketches which I made during the summer of 1890 while enjoying the 
privileges of Mr. Agassiz’s laboratory at Newport, R. I., are of suffi- 
cient interest to warrant their being published. They relate to a case 
of a peculiar bud formation in Polygordius. The larve of this anne- 
lid were very abundant for several weeks both before and after the 
dates here mentioned, and after this abnormal individual was observed 
all the tow that was brought into the laboratory was carefully exam- 
ined for similar specimens, but none were found. 
Figure 1 represents the larva as it appeared when first seen on 
_ August 9. The body was about equal in length to the longest axis of 
_ the head. So far as could be seen the head differed in no respect from 
that of the normal larva. 
The bud was situated on the dorsal side of the body close behind 
— the head, and was about equal to the body in both length and diame 
_ ter, though as shown by the figures it was quite markedly club-shaped, 
the larger end being distally directed. The outer layer of the bud 
Was distinctly continuous with the corresponding layer of the body, 
though neither at this nor at any later stage did it show anything of 
the superficial ring-structure or of the pigment spots, such as were 
open a 
sparse all around from te exteoal wal of the bud by an empty 
