the eurypterids which in the Upper Siluric were the lords of the sea, were now put largely on the defensive. Fritsch has contended [1904, p. 77] that Glyptoscorpius is but an eurypterid and that the supposed combs are merely long fringes at the posterior margins of abdominal segments, and if this is correct then this genus may represent an extreme development of Anthraconectes.
The third feature which the Carbonic species have in common is the exaggeration of the development of the epimeral pieces of the abdominal segments, well seen in the figure of E. mazonensis on the left side [text fig. 50]. E. mansfieldi shows the same features very clearly 
Figure 49 Eurypterus approximatus Hall & Clarke. Copy of original figure [text fig. 44] and E. approximatus possessed long and recurving epimera on the preabdominal segments (the postabdominal segments are not satisfactorily preserved in the single type). These epimeral pieces are produced into strong recurving spines [text fig. 49] and the character is hence entirely in line with the spinosity of the surface, increasing the gerontic aspect of these species.
Another important distinctive character is the lack of differentiation between the first three pairs of endognathites and the last pair. This is especially distinct in E. mansfieldi [text fig. 43]. Finally these species of Anthraconectes were fresh or brackish-water animals while the true Eurypteri were marine.
Even if the characters of the opercular appendage noted by Meek and Worthen should not warrant the recognition of this subgenus, the features mentioned which are common to the majority of the Carbonic Eurypteri are fully competent to verify their suspicion that "other characters will be found showing it to belong to a distinct subgenus—if not indeed to an entirely distinct genus from Eurypterus proper." It is on the sum of these characters that we would base the subgenus Anthraconectes.
