THE EURYPTERIDA OF NEW YORK 329 
segments of the endognathite, the peculiar character of the scales and the 
longitudinal ridges of the segment. 
The multispinosity of the segments is a notable character of 
the genera Stylonurus and Dolichopterus and of a few rather aberrant 
species of Eurypterus and Eusarcus. The arrangement of the spines 
in Megalograptus is rather bunched and in this regard differs from the 
prevailing serial arrangement in Stylonurus and Dolichopterus, and resem- 
bles more that of the apparently aberrant Eurypterus dekayi. 
The ornamentation consists of circular to oval rings with deep central 
pits. The ragged edges of the rings show, however, that they are of sec- 
ondary origin, and since in some places the original scales are preserved, 
it is seen that the rings originate where the flat or slightly depressed top 
of the scales is broken away. The scales, where well preserved, strongly 
suggest the circular disklike scales so characteristic of Eusarcus. They might 
result from the compression of such wartlike scales as are present in the 
aberrant Eurypterus pustulosus, and they may also lead to 
the droplike suboval scales of Echinognathus and of Stylonurus. The 
comparison with the latter genus is fortified by the presence of strong 
longitudinal ribs on the segment which is correctly considered by Mr 
Foerste as belonging to the postabdomen. 
Family PreRyYGOTIDAE nov. 
Genus HUGHMILLERIA Sarle 
The genus Hughmilleria was erected by Sarle in 1902 for the common 
species of the Pittsford shale which is thought by its author to show close 
relation to Pterygotus though in many ways suggesting the genus Euryp- 
terus. The following is the original generic diagnosis: 
General outline lanceolate. Cephalothorax semielliptic and flatly 
convex; compound eyes small, subelliptic and marginal; ocelli subcentral. 
Abdomen divided into distinct anterior and posterior regions. Preab- 
domen provided dorsally with six plain, transverse, ‘bandlike tergites; 
ventrally with five sternites, the last three being essentially like the cor- 
responding dorsal plates. First sternite cleft for the reception of a median 
appendage, which varies in form according to sex. Basing sexual dis- 
