12 PEOCEEDIXGS OF THE NATIONAL MTTSEUM. vol.64, 



groove shallow and slightly marked below head, becoming much 

 deeper with abrupt sides and rounded bottom beyond line of incisura 

 capitis to end abruptly with steep terminal wall at level of outer 

 margin of tuberculum inferior, passing in a nearly straight line 

 across humerus at slightly less than a right angle (distally) to axis 

 of shaft ; proximal margin of groove opposite incisura capitis slightly 

 arcuate with a slight overhang; groove for deltoid beginning at 

 anterior margin of insertion for pectoralis major, and extending as 

 a deep groove with abrupt margin on bicipital side, where there is 

 an overhang on lower half, to become more shallow and merge in a 

 curve with coraco-humeral groove; bicipital surface shorter than 

 broad, irregular, delimited below by an impressed line extending 

 transversely from lower margin of inferior crest in a slight curve to- 

 ward distal end of deltoid groove to end near center of shaft ; tubercu- 

 lum inferior triangular in outline, elevated, square at point ; shaft on 

 lower surface compressed to form a sharp, angular line extending 

 to base of caput humeri, excavated on lower side, in an elliptical de- 

 pression below caput humeri where the margin of the humeral head 



forms a slight overhang; tuberculum 

 externum elongate, prominent, exca- 

 vated at median point so that the sur- 

 face is concave, extending proximally 

 to margin of bone, and forming a 

 slight anterior projection at base of 

 Figs. 6 and 7.— Head of humerus caput humeri; fossa subtrochanterica 

 i:^s'''\:LTr\tr^oT.ZZ sipping gradually from side of shaft, 

 YiBws. ( X 2.) comparatively shallow, though over- 



hung by elevated tuberculum inferior ; no pneumatic foramen ; a sharp 

 compressed ridge extending inward obliquely to shaft, with a low 

 rounded ridge passing from point of junction with shaft to base of 

 overhanging caput humeri, the latter line delimiting a small con- 

 cavity, rudely triangular in outline, at base of incisura capitis, and 

 forming the inner margin of the median depression below the artic- 

 ular head; viewed laterally the inferior tubercle slightly hooked; 

 posterior line of crista inferior joining shaft at an oblique angle, 

 with outer margin shallowly concave near center. 



Measurements in millimeters. — Length from outer end of bicipi- 

 tal groove to end of caput humeri 7.1; greatest breadth of head 7.7; 

 height of crista superior above lower margin of shaft 3.5. 



Range. — Upper Pliocene: Known only from type locality 2 miles 

 south of Benson, Cochise County, Arizona. 



RemarTcs. — This species represents a sandpiper very closely allied 

 to the modern stilt sandpiper {Microjjalama himantopus) that at 

 the present time breeds from near the coast of Mackenzie for an 

 indeterminate distance southward, and ranges in migration through 



