THE EURYPTERIDA OF NEW YORK 219 
Tylopterus boylei is known in only a single specimen pre- 
served as a mold of the dorsal surface. Guttapercha squeezes of this show 
that the knots are not located on the first to fourth segments as stated 
in the original description but on the second to fifth. The squeezes also 
show distinctly the ocelli on the prominence between the lateral eyes. 
On the right side also two segments of the fourth ectognathite (balancing 
leg) are seen and on the opposite side the edges of two flat segments, appar- 
ently the oar plate of the swimming leg. The legs seem, therefore, to 
have agreed with those of Eurypterus. 
Subgenus ANTHRACONECTES Meek & Worthen! 
Meek and Worthen suspected that their species Eurypterus 
-mazonensis from the Lower Coal Measures (Pennsylvanian) repre- 
sented a distinct subgenus, if not a genus, for which they proposed the name 
Anthraconectes. They state. that this fossil ‘‘ differs from the typical 
forms of Eurypterus particularly in the great length and single extremity 
of the mesial appendage of its operculum, as well as in the possession of 
66 
two little spatulate supplementary pieces.’”’ Hence they ‘strongly suspect 
that other characters will be found, when better specimens can be studied, 
showing it to belong to a distinct subgenus, if not indeed to an entirely 
distinct genus from Eurypterus proper.” | 
Hall suggested that these differences may not be of great importance 
_ [op. crt. p. 26] and emphasized the fact that the species from the Pennsy]l- 
vania Carbonic are typical Eurypteri [p. 27]. 
While we agree with Meek and Worthen that the peculiar character 
of the opercular appendage would warrant a separation of the species 
from typical Eurypterus, we believe that the preservation of this organ 
is not so distinct that its characters are beyond doubt. On the other hand, 
we have no doubt that Anthraconectes mazonensis hasa 
number of characters in common with the Pennsylvania and also with 
British Carbonic species which distinctly indicate a phylogerontic condition 
1See Appendix, 
