. The Eurypterida of New York. Eurypterida; Paleontology. 144 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 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-
. The Eurypterida of New York. Eurypterida; Paleontology. 144 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 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, whil6 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. Figure 29 Early stage in development of scori>ion. Ventral view of embryo, af, eye fold; sa, lateral eyes; obi, upper lip; Km. comb (pecten); abp, ab- dominal legs (gills). (From Brauer). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Clarke, John Mason, 1857-1925; Ruedemann, Rudolf, 1864-1956. Albany, New York State Education Department
Size: 1131px × 2210px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecad, booksubjectpaleontology, bookyear1912
