92 THE DEVONIAN OF MISSOURI. 



In the brachial valve the fold originates about the middle of the shell in young 

 specimens and is low and inconspicuous. The beak is short and incurved against the 

 opposite valve. The plications are similar to those on the opposite valve — five plica- 

 tions on the fold. The median septum extends forward about 1/3 the length of the shell. 



Occurrence — Rare in the Callaway limestone of Callaway County. 



Genus Pugnoides Weller 



Pugnoides alius (Calvin) 

 Plate 16, figures 10-12 



1875. Ryhnchonella alta Calvin, paper read before the Iowa Acad. Sci., and a named 



photographic plate distributed. 

 1890. Rhynchonella pugnus, var. alta Williams, Bull. Geo. Soc. Am., I, pi. 12, figs. 5-7. 

 1894. Pugnax alius Hall and Clarke, Pal. New York, VIII, pt. 2, p. 203, pi. 60, figs. 



1-5. 

 1897. Pugnax pugnus alta Schuchert, Bull. U. S. Geol. Surv. 87, p. 335. 

 1909. Pugnax altus Greger, Am. Jour. Sci., 27, p. 376. 

 1913. Pugnax pugnus var. altus Clarke and Swartz, Maryland Geol. Survey, Middle 



and Upper Devonian, pp. 583-584, pi. 54, figs. 17-22. 

 Description — Shell subelliptical to subcircular; length and breadth subequal; 

 greatest width near the middle. Pedicle valve slightly convex near the hinge, with a 

 sinus beginning near the middle and becoming deep at the front. Beak prominent, 

 slightly incurved, projecting slightly beyond that of the opposite valve. Brachial valve 

 more convex than the pedicle; fold beginning near the front and only slightly elevated. 

 Plications coarse, usually 2 in the sinus, 3 on the fold and 2 or 3 on each lateral slope. 

 In most specimens the plications are marginal but in some they extend to the middle of 

 the valve. 



Remarks — This is a rare form and during the investigation it has been collected 

 only from the Craghead Creek locality from a thin bed of shale near the top of the 

 Snyder Creek shale. As it has a median septum in the pedicle valve, it belongs to 

 Weller's genus Pugnoides. 



Pugnoides swallovi n. sp. 



Plate 16, figures 13-15 



Description — Shell small, subtriangular in outline, usually slightly longer than 

 wide, the greatest width anterior to the middle, usually thin but in some cases thick. 

 The dimensions of three specimens are: Length 8 mm., 7mm., 6 mm.; width, 8 mm., 

 6 mm., 7 mm.; thickness, 7 mm., 5 mm., 3 mm. 



Pedicle valve slightly convex; beak pointed and slightly incurved; sinus shallow and 

 present only on the anterior margin; a projection of the front of the sinus reaching far 

 into the brachial valve; median septum about one-third the length of the valve. 



Brachial valve slightly convex, highest at the front margin; beak small, incurved 

 below that of the pedicle valve; mesial fold low and present only near the front margin; 

 a well developed median septum for about half the length of the valve. 



Plications on the smaller shells inconspicuous, on the larger 2 to 3 in the sinus, 

 3 on the fold, and 3 to 5 each side of the fold and sinus. The best developed plications 

 extend less than half the length of the shell. No other surface markings appear on the 

 specimens studied. 



Remarks — This is a rare form, only 5 specimens having been collected. It does not 

 resemble closely any other species from the Devonian of America. 

 Occurrence — Mineola of Montgomery and Ralls Counties. 



