Morse,] 304 [March 19,. 
ments, the anterior one small and running back on the second ses- 
ment. On one embryo he found two red eye-spots on the first 
segment, while on another embryo he found four red eye-spots. In 
the same number of rings, the peculiar form of the cephalic ring, 
and if Oscar Schmidt is right, the attachment of the embryo by the 
caudal segment, we observe the closest similarity between the embryo 
of this Brachiopod and that of Melicerta ringens, figured by Hux- 
ley ; 
It will be seen by the accompanying figures of the embryo of The- 
cidium, copied from Lacaze-Duthiers, and the embryo of —Velicerta 
ringens, thatin the Rotifer embryo the body is drawn out, while in 
Thecidium it is condensed. 
For several years I have endeavoured to secure some data regard- 
ing the embryology of Terebratulina, and in the early summer of 
1872, I had the good fortune to find Terebratulina spawning. The 
eges were round and ciliated, and had the peculiar pencil of long 
cilia so peculiar to the embryos of many worms. The body was 
gradually cut up into three deeply constricted segments, and these at 
a later stage had the characteristic vermian contraction, the rings 
shortening upon themselves and then gradually expanding. Though 
I made several hundred drawings from fifty different embryos, yet - 
1 Jour. Mic. Soc., Vol. 1. 
2 Since this paper was in type, I have again visited Eastport, Maine, and have had 
an opportunity of studying the embryology of Terebratulina under more favor- 
able circumstances. I have only room here to state that after swimming actively 
for a while the segmented embryo becomes attached by the caudal segment which 
is to be the peduncle, the middle or thoracic segment increases in diameter, one 
portion becoming more prominent; the first or cephalic segment continues to move 
and bend on the thoracic segment. Meanwhile the thoracic segment grows rap- 
idly at cpposite points, and finally engulfs the first segment by lobes above and 
below, these lobes being the dorsal and ventral valves. The mouth becomes appar- 
ent, and at the same time two groups of sete make their appearance on the sides 
and front cf the lobes, these are delicately barbed and deciduous. 
The relations pointed out on pages 29 and 30 regarding the cephalic collar of the 
Annelids and the pallial membranes of the Brachiopods receives confirmation in this 
unlooked for simple developement of Terebratulina, and so far as these forms are 
concerned, we can for the first time state positively that the mouth and arms rep- 
resent the first segment, the pallial membranes with the shells, the second or 
thoracic segment, while the peduncle represents the caudal segment. 
The first three tubules in the shell are bordered by long delicate hairs, indicating 
that these are sense organs as in the tubules of certain crustacea, surrounded also 
by hairs as described by De Morgan, see p. 16. Regarding barbed setz, see page 21. 
These results were communicated to the Boston Soc. Nat. Hist., June 18th, 1873, 
and will soon be published in their Memoirs. 
