530 H. Woodtvard — 07i Goniocypoda Edwardsi, 



sometimes — as their contained fossils prove — marine conditions pre- 

 vailed, at another freshwater, at a third estuarine. But whatever 

 these conditions were, the contained organic remains indicate a 

 warmer climate than is enjoyed by us in the same latitude at the 

 present day. 



The Crab which forms the subject of these remarks was collected 

 by Mr. B. Porter, and now forms a part of the geological collection 

 in the British Musuem. It is preserved in a small slab of Eed 

 Marl or Clay, having the dorsal aspect exposed to view. The 

 counterpart or intaglio is also preserved, and affords some additional 

 details. 



Diagnosis of the genus Goniocypoda. — Carapace quadrangular, nearly 

 one-third broader than long, tumid, borders rounded, surface granu- 

 lated sparingly, regions of carapace but little distinct from each 

 other ; lateral border of carapace entire, deep, forming nearly a right 

 angle with dorsal surface, posterior border straight, anterior angles 

 curving inwards and terminating in the external orbital angle : 

 rostrum small, square : front border of carapace nearly straight 

 and occupied by the orbital fossae ; eye-stalks long : fore-arms short, 

 feeble ; thigh of walking-legs broad and flattened, and slightly ser- 

 rated at distal end : feet formed for running, (The Abdomen and 

 antenna, if present, are concealed in the matrix) . 



I have carefully compared this Eocene Crustacean with Grapsus, 

 Gonoplax, Macroplithalmus, Gelasimus, and Ocypoda. It differs from 

 Grapsus in the absence of dentations on the latero-anterior border, 

 in the greater lateral breadth of the carapace behind, and in the 

 greater length of the eye-stalks. It approaches Grapsus only in the 

 form of the limbs, and the smallness of the hands. Goniocypoda is 

 distinguished from Gonoplax by the more rectangular form of the 

 lateral and posterior borders, and by its short, somewhat thick hands 

 and chelge. 



From Gelasimus and Gonoplax it also differs, in having the latero- 

 anterior angles of the carapace curved in towards the external orbital 

 angle. Compared with Macroplithahnus the relative proportions of 

 the length and breadth of the carapace are much the same ; but 

 Goniocypoda differs from MacropMhalmus in the same point as it does 

 from Gonoplax and Grapsus ; namely, in the absence, in the fossil, 

 of dentations along the latero-anterior border. 



The form of the rostrum closely corresponds with MacropWialmus 

 and Ocypoda ; and in both genera the orbital fossee occupy the whole 

 breadth of the front of the carapace ; they are much curved in the 

 two recent genera, but nearly straight in the fossil. The cara- 

 pace in Ocypoda is almost equilateral, in Goniocypoda it is one-third 

 broader than long. 



Goniocypoda Edivardsi (PI. XXI. Fig. 1.) — This neat little crab, is 

 smaller than the Macrophtlialmus dilatatus of De Haan, the carapace 

 being eight lines in greatest breadth, and five lines only in length : 

 the rostrum is only one line in width, and projects the same distance 

 in front, being bent downwards as in Ocypoda: the eye-peduncles 

 are two lines in length, and are but slightly curved : the external 



