392 PALAEONTOLOGY OF NEW-YORK. 
AFFINITIES OF THE GENUS EURYPTERUS. 
Dr. Dekay, in his original observations on Eurypterus , referred the fossil 
to the Branchipodal Crustacea (Entomostraea), and has indicated the 
Genera Arus, Binoculus and Lepidurus as the forms to which it seems 
most nearly allied ; and later writers have expressed similar views of the 
relations of this fossil*. 
Burmeister ( op. cit.) has shown the analogies of the Trilobites with 
the Phyllopoda, in three of the principal genera, Apus, Branchipus and 
Limnadia ; and he suggests that the Eurypterus was a shelless trilobite, 
as Branchipus is a shelless phyllopod. The Eurypteridete are arranged by 
him as a family with Cytherinidese and Trilobitse, under Palaeadae. 
Dr. F. B(EMer has suggested the affinity of Eurypterus with Limulus; 
indicating, however, the great difference in the feet, etc. Prof. M‘CoYf 
has adopted the same opinion, and has united the Eurypterus and Ptery- 
gotus in the Family Eurypterideee ( Burmeister). 
Mr. Huxley|, in his observations on the structure and affinities of Hi- 
mantopterus ( = Pterygotus ), remarks that “Analogies, if not for Himanto- 
* Dr. Harlan has adopted the descriptions and references of Dr. Dekay without comment, as to 
the relations of the fossil among the Crustacea; while Dr. Hibbert* has cited Dr. Harlan as 
follows : “ The Eurypterus is assigned by Dr. Harlan to the Class Crustacea and to the Order 
“ Branchipoda. His description is as follows”. Here is given the original description of Dr. Dekay, 
and then he says : “ Dr. Harlan’s specimens were obtained from a transition calciferous sandrock 
“ of Westmoreland in the Oneida county of New-York. He has described two fossil species, the 
“ Eurypterus lacustris and the E. remipes ( See Plate xii, figs. 6 & 7)”. 
I cite this, to correct both the error in giving Dr. Harlan as the original authority for these two 
species, and also the erroneous reference to localities, as will be seen by consulting the paper of Dr. 
Harlan. 
Mr. Salter says (Quarterly Journal of the Geological Society, Yol. xv, p. 230) : “ Dr. Harlan, 
“ too, in his Medical Researches [Medical and Physical Researches], had given similar hut rather 
“ more perfect figures of two species from Williamsville, Buffalo, in the State of New-York”. The 
truth is, Dr. Harlan has given a figure of Dr. Dekay’s species E. remipes copied from the original 
figure in the Annals of the New-York Lyceum, as expressly stated by him, for the purpose of com¬ 
parison with the proposed species E. lacustris, which is less perfect than the figure of E. remipes. 
f British Pakeozoic Fossils, page 175. 
f: Quarterly Journal of the London Geological Society, Vol. xii, p. 35. 
Transactions of the Royal Society of Edinburgh, Vol. xiii, p. 281. 
