470 General Notes. 
EMBRYOLOGY.? 
EMBRYOLOGY or [Nsects AND ARACHNIDs.’—Under this title, 
the friends of the author have issued the results of studies made by 
the late Dr. Adam Todd Bruce upon the embryology of Thyridop- 
teryx, Chrysopa, Meloe, Mantis, the Grasshopper, Musca, and an 
undetermined spider. The most, complete observations were made 
upon the development of Thyridopteryx, where Dr. Bruce failed to 
find the centrolicithal segmentation described as characteristic of 
arthropod embryology, but rather a central segmentation, the blas- 
em 
from the lateral thickenings. The maxille in the embryo are 
triramose. 
In the fly, observations were recorded on the development of the 
_ egg and its maturation, Dr. Bruce regarding the yolk as arising 
from the breaking down of the epithelium of the outer end of the 
ovarian tube. : 
In the spider, Dr. Bruce found the invagination for the optic 
vescicles (vide PI. vi., Figs. lxxx and lxxxi.) ; but he erred in calling 
it the amniotic fold, otherwise (as he published a preliminary ere 
in which this fold was mentioned) he might have anticipated Locy 
in his discovery. Some observations are recorded upon the forma- 
tion of the pulmonary organs, but, from reasons not apparent 1n 
either figures or text, the author thinks that two appendages are 
concerned in the formation of each lung-book. It is, however, to 
be noted that his observations, so far as they go, show that the lung- 
books are in reality modified appendages, and support the hypo- 
1 Edited by Prof. Jno. A. Ryder, University at Penns Philadelph 
2 Observations on the Embryology of Insec rachn 
dam Todd Bruce. Baltimore, 1887. 4to; 9x31x17 pp.; 7 plates and 
