266 NEW YORK STATE MUSEUM 
cordiform.”’ Its length is more than half that of the carapace, its greatest 
width (in the anterior fourth) one half of its length. It decreases slightly 
in width posteriorly. Its lateral margins are nearly straight or but slightly 
concave. Its posterior end is transversely truncate, slightly emarginate in 
the middle. | 
Figure 61 Dolichopterus macrochirus Hall. Outline sketch 
of the ventral appendages of the type specimen. Natural size 
The opercular appendage of the female is seen very imperfectly in 
Hall’s type. It is better shown in the specimen in the museum of the Buffalo 
Society of Natural Sciences [pl. 44]. It is similar to that of Eurypterus, 
differing mainly in the greater length and less curvature of the paired 
terminal pieces. The proximal portion has not been distinctly seen. 
- Traces of the pentagonal areas and the inclosed hastate proximal 
