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NEW YORK STATE MUSEUM 
Embryology] and one of Brauer’s’ figures. Study of these shows that 
the carapaces of the larval eurypterids have a closer agreement with 
Figure 29 Early stage in development of scorpion. 
Ventral view of embryo. aj, eye fold; sa, lateral 
eyes; obl, upper lip; Km, comb (pecten); abp, ab- 
dominal legs (gills). 
(From Brauer) 
Limulus than with the scorpions. 
In the scorpion embryo and larvae 
the carapace is relatively of larger 
size than in the eurypterids, being 
nearly half the length of the em- 
bryo, but it is long and slender, 
instead of short and broad or semi- 
circular as in the merostomes; the 
procephalic region early exhibits 
a deep frontal emargination and, 
according to Metschnikoff, a dis- 
tinct bilobation, features that are 
found in neither Limulus nor 
the eurypterids, but which are 
characters of the adult scorpion. 
Likewise the development of the 
cephalothoracic appendages, while 
homologous in number and orig- 
inal position as to the stomodaeum 
(embryonic mouth) to that of the 
merostomes, differs from that of 
the eurypterids and Limulus in the 
early development of the pedipalps 
of the second segment, correspond- 
ing to their prominence in the adult 
scorpion. They are even recog- 
nizable earlier than the chelicerae 
of the first segment, whilé the fol- 
lowing four pairs of walking legs 
are of uniform size and character. 
The homology of the appendages of the cephalothorax repeats 
itself in the abdomen; here again the number is absolutely in agreement 
