, 
’ 
4 
Geology and Natural History. 471 
Hill do not make a thirtieth of its length. The true typical Ta- 
conic is therefore not the quartzite portion, but the slates and lime- 
stones of the Taconic range, as he has directly declared. In fact, 
there is some reason for believing that this quartzite portion un- 
derlies the rest of the Taconic rocks of the section unconformably, 
and hence never was rightly a part of the Taconic series. Whether 
this last be true or not, the name Taconic belongs only to the era 
represented by the rocks of Taconic mountain, about which and 
out of which the system was engendered. 
Professor Emmons is deservedly honored for combating the 
system so unscientific, that his opponents had abundant reason 
for their doubts. o one 
be nearest the truth; and no one has sufficient grounds yet for 
asserting that the “ Hudson river beds” (those above the Tren- 
ton) may not be included among the beds of the Taconic forma- 
tion overlying the Stockbridge limestone. 
8. The Development of Limulus Polyphemus ; by A. S. Pack- 
ArD, Jr., M.D. 48 pp. 4to, with 3 plates. Memoirs Bost. Soc. 
Nat. Hist. (Printed without date.)—In this memoir, Dr. Packard 
makes an interesting and very important addition to our knowl- 
edge of the embryology of the Crustacea, in tracing the develop- 
ment of the horseshoe, or king-crab, of our coast. he changes 
tion to embryology, we cannot quite agree with the views of 
homologies and classification taken by the author. 
Dr. Packard regards Limulus and all the Merostomata as 
