156 NEW YORK STATE MUSEUM 
and E.? (Dolichopterus) stellatus from the Frankfort shales 
complete the list of North American representatives of the genus.! 
In Europe a considerable number of species were described by Salter 
and Woodward but the principal advance in the knowledge of the genus 
and its structural details has been made by F. Schmidt [1883] and Holm 
[1898]. Both of these authors described the E. fischeri from Oéesel, 
which had already served as the subject of Nieszkowski’s investigations 
and was at that time identified with E. remipes DekKay. Schmidt 
corrected and supplemented in many ways Hall’s and Nieszkowski’s de- 
scriptions of the endognathites, demonstrated the presence of five separate 
sternites (Hall knew but one, the operculum, and Nieszkowski assumed 
six) and showed that they are open on the ventral side. He further pointed 
out differences in the appendages of the first and second sternites in indi- 
viduals otherwise alike and attributed these to sexual differences. In the 
dolomite marls of Oesel these merostomes are not preserved as in the 
waterlimes cf New York where the integument is fully carbonized. By 
most skilful manipulation Holm succeeded in removing from the matrix 
the integumental film of E. fischeri and was thus enabled to study 
these parts by transmitted lght, and to describe the structure of the 
integument with a completeness that could be equaled only from the 
living organisms themselves. We shall not here enter upon a detailed 
review of the results of his investigations, but shall point out the more 
important of the determinations, since there is no reason to doubt that 
entirely similar structures existed in the closely related species HE. remi- 
pes and E. lacustris. Indeed, our material verifies several of 
his detailed discoveries referred to below. 
The absence of facets in the compound eyes was conclusively shown 
by transmitted light. On the underside of the cephalothorax the presence 
-E. pulicaris Salter [1863] from the Devonic plant beds of St John, New 
Brunswick, is based on two minute postabdomina that are insufficient for generic de- 
termination and probably do not belong to the eurypterids. 
