54 SYSTEMATIC ARRANGEMENT 



furnished with five joints; and the succeeding rings seem to have borne similar leaf-Uke 

 feet of an equal size. The abdomen consisted of three or six rings, and was terminated by 

 a pair of rudder-fins (?). 



There is only one genus belonging to this family, and of this there seem to be three 

 species. 



EuRYPTERUS, D^kay. 



1. E. remipes : Somewhat slender, the terminal joint of the large fin-feet equal in length to the 

 preceding. Length of body SYs", breadth at the upper part 1)4". 



Reference. — D^kay, Annals of the Lyceum of Nat. Hist, of New York, i, 12, 291, Plate 

 XIV; and 375, Plate XXIX (1826). Froriep's Notiz. 1827, xviii, 1-3. Holl, 

 Petref 155. Bronn, Lethaa, i, 109, Table IX, Fig. 1. Harlan, Med. and Phi/s. 

 Research. 297. c.fff. Mitchell, Jm. Month. Magaz. iii, 291. 



Locality. — Slate rocks of Westmoreland, Oneida, and New York. 



2. E. lacustris : Broader than the former species, and the terminal joints of the large rudder-feet 

 much smaller. Length of body almost 5", breadth 2^". 



Bef. — Harlan, as above, 298. c.fy. 



Loc. — The grauwacke rocks at Williamsville, seven miles from Buffalo, U. S. 



3. E. tetragonopfithahnus .■ Eyes placed at a greater distance from one another, quadrangular (?), 

 the whole of the structure very slender, especially that of the abdomen, the joints probably acutely 

 angled. Length nearly two inches, breadth %. 



Ref.—G. Fischer, Bullet, de la Soc. Imp. d'Hist. Natur, de Moscou, 1839, ii, 127, Plate 

 VII, Fig. 1 ; and his Notice sur I'Eurypt. de Podolie, etc., Moscow, 1839, 4. 



Loc. — The transition limestone or grauwacke sandstone of Podolia, at the village 

 of Zvilevy, twenty wersts to the south of Kamenetz. 



It is probable that the fossil described by Scouler under the name of Eidotea, may 

 belong to a species of this genus. Fragments of it only are known, and these correspond 

 with the head and the commencement of the thorax of Eurypterus, but certainly belong to a 

 different species. See the following works respecting it: Cheek's Edinb. Journ. of Nat. 

 Science, 1831, June, N. S. iii, 352, Plate VII. Leonhard and Bronn's Jahrbuch, 1832, 

 251. Bronn, Lethcea, i, 109, 98, Table IX, Fig. 2; and Hibbert, Transact. Roy. Soc. of 

 Edinb. 1834. This latter reference I have not had the opportunity of verifying. 



