386 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 52. 



illipeds broad and flat, but advanced beyond the front. Chelipeds 

 elongate, merus large, palm small, fingers ^ very long. Last leg very 

 small, subdorsal. 



DAKOTICANCER OVERANA, new epecies. 



Plate 32; plate 33, figs. 6-14. 



Type-locality. — South Dakota: Indian Creek, Pennington County; 

 Pierre Shale; Upper Cretaceous; August, 1914; W. H. Over; two 

 specimens, holotype and paratype, presented by the University of 

 South Dakota, Vermilion, South Dakota. 



Holotype.— Cat. No. 32055, U.S.N.M. 



Additional material. — More than 80 specimens were collected at 

 Eastern, Corson County, South Dakota, in the Pierre Shales, by 

 W. H. Over, July, 1915. Most of these are in the University of South 

 Dakota, but a series of 30 have been presented to the United States 

 National Museum. 



Measurements. — Holotype, width of carapace, 30.2; approximate 

 length, 26; approximate thickness, 10; width between the outer 

 angles of the orbits, 15.4 mm. 



Description. — There is no complete specimen even of the carapace, 

 so that this description is a composite from a number of specimens. 

 Carapace thick, transversely suboblong; gastro-cardiac area separ- 

 ated by a deep and angled groove from the branchial and hepatic 

 regions, which are deeply separated from each other; a broad, deep, 

 transverse branchial groove is continued forward on the nearly ver- 

 tical side-wall of the carapace toward the buccal angles; a broad, 

 shallower groove furrows the side-wall just below the hepatic region; 

 a depression follows the posterior and lateral margins of the carapace 

 just within the edge. The most elevated portions are covered with 

 small granules; the intermediate areas, comprising the greater part of 

 the surface, are smooth and finely punctate; the longitudinal, granu- 

 lated band on the gastro-cardiac is not interrupted by the narrow, 

 shallow groove which separates those two regions from each other. 

 The inner angle of the branchial region is prolonged backward and 

 inward in a narrow, raised peninsula, nearly surrounded by deep 

 impressions and pits. The anterior part of the carapace is divided 

 by shallow depressions into longitudinal areoles, four on either side 

 of the middle, of which two are gastric and two hepatic. Posterior 

 margin granulate and slightly arched, meeting the side margin at a 

 rounded angle. 



» The character of the fingers is given with a reservation. Of the many specimens taken, only one shows 

 a trace of fingers, and these exhibit such an unusual shape that although they are in the position where one 

 expects fingers, i. e., bent against the arm, it may later be proven that they are, for example, merus jomts 

 of ambulatory legs. On the other hand, the fragility resulting from their great length and relative slender- 

 ness may account for the destruction of all the fingers which this large collection of crabs possessed. 



