GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 167 



.areolation and. ornamentation of the central part of the carapace 

 which indicate an affinity with Callinectes. 



EUPHYLAX FORTIS, new species. 



Plate 64, figs. 11-13. 



Type-locality. — Banana Elver, Costa Rica : tenth fossilif erous zone 

 below the uppermost one of the section. Probably equivalent to 

 Gatun formation. Miocene series. D. F. MacDonald, collector. 

 October, 1911. Station 5S82&. Cat. No. 324233, U.S.N.M. 



Measurements. — Length of body (approx.), 43.5 mm.; length of 

 movable finger, 27.3 mm.; width of the sternum between the coxae 

 of the chelipeds, 24.5 mm. 



Ilolotype. — One specimen showing a part of the lower surface 

 and the right' cheliped. The abdomen resembles that of an imma- 

 ture female or is possibly that of a male. 



Sternum broad, surface rough with coarse punctae and fine reticu- 

 lating lines ; anterior part depressed and with a median groove lead- 

 ing back to the abdomen much as in E. callinectias; the ridge just 

 in front of the abdomen is more transverse than in that species. 



Abdomen broadly triangular; it is impossible to tell which seg- 

 ments, if any, are fused; terminal segment subequilateral ; surface 

 of sixth and seventh segments like that of the sternum, of fourth 

 and fifth segments covered with a low, confluent granulation. 



Ischium of external maxilliped with a longitudinal groove, the 

 surface on the inner side of the groove more raised than on the 

 outer side. 



Cheliped elongate. A cross section of the arm is shown and a 

 portion of its lower surface; this last has a broad longitudinal de- 

 pression through the middle, and the surface near the margins, at 

 least, is coarsely granulate. 



The general outline of the fingers can be made out and the sur- 

 face of some of the prehensile teeth. The fingers are elongate, as 

 in the usual Portunicl, and gradually taper, ending in slender black 

 tips which cross each other. The prehensile teeth are large, thick, 

 dark- colored, and very irregular, the one at the base of the dactylus 

 being the largest; they appear to fit close together. The cheliped 

 is larger and stronger in proportion to the size of the body than in 

 any recent species of Portunid. 



The generic position of this species is problematical ; in the width 

 of the sternum it resembles Euphylax; in the strong teeth of the 

 digits it approaches Scylla, while the groove on the lower side of the 

 arm joint is unique. 



