40 Annals of the Carnegie Museum, 



with a ratio of width to height of i : .87. A smaller specimen has a 

 width of 19 mm. and a height of 15 mm., and a ratio of i : .79. The 

 range in the ratio of width to height is from i : .77 to i : .89. 



The valve of the pedicle is gibbous a little below the umbo, and 

 curves evenly to the sides. It becomes flattened in the middle and is 

 deeply sinuate toward the front of the shell. The beak is closely 

 incurved over the umbo of the brachial valve. 



The brachial valve is more convex than the pedicle and curves to 

 the sides, with a bro^d, flattened mesial fold, well-developed from the 

 upper third of the shell. 



The surface is marked by fine concentric striae and also by fine 

 radiating striae, which are usually most prominent on the sides of the 

 shell. From three to seven low, rounded plications occur in the sinus, 

 and from four to eight in the fold. The specimens usually have from 

 one to three low, rounded plications on the sides of the valves, which 

 diminish in relief toward the lateral margins. All of the plications 

 radiate from the beaks and they are almost invariably clearly defined 

 from the beaks to the margin of the shell. This new variety difi"ers 

 from Leioi'Jiynchiis madisonense in the greater convexity of the valves; 

 the normally greater number of plications in the fold and sinus, and 

 in the height and width being more nearly equal. 



This new variety differs from Leiorhynchus kellogi in the lesser 

 number of plications on each side of the fold and sinus, and in having 

 the plications extending all the way from the margin to the apex, 

 instead of half-way or less, as in L. kellogi. The type is in the Carnegie 

 Museum. 



Locality. — Specimens are numerous in the gray limestone, number 4, 

 and also in the green shales, number 5, at Three Forks, Logan, and 

 the other localities in that region. Twenty-four specimens were 

 collected by Dr. Raymond in 1905 and seventeen by the writer in 

 1912, and about ten in 1913. 



12. Leiorhynchus utahense var. ventricosum var. nov. (Plate VIII, 



figs. lo-ii.) 



Cf. Leiorhynchus ulahensis Kindle, Bull. Am. Pal., No. 20, p. 27, PI. 3, figs. i-ic. 

 Cf. Leiorhynchus greeneanum (Ulrich), Cont. Am. Pal., I, 1886, p. 26, PI. 13, fig. i. 



Shell large, ventricose on brachial side, and flattened on side of 

 pedicle. Ratio of width to height i : .94. Thickness usually some- 

 what less than height. The type specimen has a width of 37 mm., 



