EURYPTERUS. PPP. 33 



tively very long, being six time^ as long as wide; the ex- 

 tremity is divided into four lobes, two of which form the ex- 

 tremity proper, while the other two are Just anterior thereto. 

 The lobes are triangular, and the anterior pair are orna- 

 mented with five or six strong plications. In the angle be- 

 tween the distal pair is a short process which may be the 

 point of attachment of a small terminal appendage. Other 

 parts of the epistoma unknown. Two of the maxillse have 

 been observed in position ; tliey do not differ conspicuously 

 from other described forms of the genus. 



Metastoma ovate, bilobate at the smaller end. 



Surface ornamented with minute imbricating scales. On 

 the posterior tergal portion of each somite the scales are 

 larger and triangular. The lateral processes of the first six 

 segments and lateral margins of the carapace are marked 

 by sharp, oblique striae. The i:)rocesses of the posterior 

 segments are nearly free from ornamentation, being some- 

 times marked by one or two strife. The telson appears to 

 be free from the characteristic ornamentation of the other 

 portions of the test. On the metastoma the scales are larger 

 and more irregular than on the segments. 



A large and nearly entire individual has the following di- 

 mensions : Extreme length from the anterior margin of the 

 carapace to the extremity of the telson, 228 mm.; length 

 of carapace, 31 mm.; width of fourth somite, 53 mm,; 

 width of last somite, 15 mm.; length of telson, 80 mm. 

 The smallest specimen observed has a length of 83 mm., of 

 which 30 mm. belongs to the telson. 



This species differs from E. sttjlus^ with which it is asso- 

 ciated, in its greater size, so far as oKserved, the more elon 

 gate form of the carapace, more api)roximate eyes, shorter 

 palpi, and compaiatively much shorter and more slender 

 telson. The cnud;il spine of E. Maiisfieldi is usually about 

 one-third the length of the entire animal, while in E. .sfi/Iits 

 it occupies nearly-one half of the entiiv length. 



E. Mazonensis, M. k ^V.. froMi the co.-il measures of 

 Illinf)is, l)ears a close restMiil)lance to this si)ecies in gen- 

 eral form and suiface oj-iianieiitation, but the carapace is 

 shorter and mo]-e regularly rounded. 

 3 PPP. 



