'S'2 VW. UKi'oiM- oi' i'K<>(;i:i:ss. .iamks hall. 

 ErKYPTKiirs Maxsfikldi. 



Pliitos IV, Figs. 1-8; V, Figs. 1-11 ; VI, Fig. 1 ; VII, Fig 1 ; VIII, Figs. 1-3. 



Dolichopterus Mansfieldi, C. E. Hall, Proc. Am. Phil. Soc. Philad. Vol. 



XVI,p.6Sl, 1877. 



Carapace semi-oval, nearly one fourth broader than long ; 

 sides oblique, nearly straight ; margin indented, distinctly 

 limited. Eyes reniform, prominent, situated a little for- 

 ward of the centre of the carapace and about midway between 

 a median line and the lateral margins. Between the eyes 

 are two broad rounded longitudinal elevations and below 

 are two similar oblique diverging prominences. 



Abdomen increasing in breadth from the carapace to the 

 fourth segment, then gradually decreasing to the seventh 

 segment, which is a little more than three-fourths the 

 width of the fourth ; the body narrows abruptly at the 

 eighth segment which is about one-half the width of the 

 fourth. The last segment is longer than wide and about 

 one-half the width of the eighth. The posterior angles of 

 the six anterior somites are acute and slightly produced, 

 the seventh is considerably extended and the five posterior 

 somites are armed with strong angular retral si:)ines. The 

 first segment is anchylosed to the carapace. 



The telson is very narrow and attenuate; its length about 

 one-third of the entire animal; extremity acuminate. 



There are four simple palpi, of which the fourth ^Dair pro- 

 ject beyond the margin of the carapace for a distance equal 

 to the width of the carapace, and expose five joints exclusive 

 of the terminal spine. The first pair expose only the last 

 two joints. The margins of the joints of the palpi are ser- 

 rated, and the outer posterior angles are produced into 

 spines. The palpi terminate in a long curved spine or free 

 dactylus. 



The large swimming feet near the carapace are comj)osed 

 of short, broad joints. The penultimate joint has a length 

 more than twice its width. The palette is elongate ellipti- 

 cal in form, with the anterior terminal margin serrate. A 

 small acute terminal plate is inserted in the ajDex. 



The median appendage of the thoracic plate is compara- 



