DESCRIPTION OF SPECIES 315 



1898. Product us i)hiUipsi Weller, Bibliographic Index of Nortli American Car- 

 boniferous Invertebrates, page 498. 



1915. Prodiictus philUpsi G. H. Girty, Missouri Bureau of Geology and Mines, 

 volume 13, series 2, page 347. 



Original description. — '^^Shell rather small, nearly as long as broad, 

 dorsal valve slightly gibbous, its anterior part flattened, with a wide shal- 

 low sinus on old specimens, while young ones do not show it. The beak, 

 although slightly enrolled on itself, does not pass the cardinal border. 

 The ears are small, flattened, and smooth, showing no trace of either 

 folds or tubes. The surface is covered with coarse, irregularly sized ribs, 

 which are generally broader than the furrows separating them. Many of 

 the ribs are bifurcated. The cardinal line measures four-fifths of the 

 greatest breadth of the shell. The sides fall perpendicularly on the ears. 

 The only traces of tubes are a few indistinct ones on the flanks. 



"Ventral valve concave, with a very slight varix. The visceral disk has 

 ribs similar to those on the other valve ; beyond the disk they are obliter- 

 ated, the surface being covered with nine or ten broad lamellae, the edges 

 of w^hich are turned sharply upward, presenting acute wavy ridges, which 

 are continued on to the cardinal border on each side.^^ 



Remarks on Amsden specir)iens. — The beak passes the cardinal border 

 in some Amsden specimens and in some the ears have incipient folds and 

 a few small spines. Six specimens give the following measurements: 

 Length, 17 to 24% millimeters; breadth, 20 to 24 millimeters; thickness, 

 6 to 9 millimeters. 



The surface of the pedicle valve is marked by about 28 ribs. Near the 

 anterior border there are from eight to ten ribs in the space of 10 milli- 

 meters. 



This species may be easily distinguished from any other by the coarse, 

 irregular ribs of the valve and by the visceral portion only of the ventral 

 valve possessing ribs, with broad, ridged lamellae around it. The pedicle 

 valve does not appear to have possessed an anterior prolongation, as its 

 present front is without one and is bounded by a sharp margin. 



Next to Composita trinuclea this is the most abundant species in the 

 fauna. 



PUSTULA GENEVIEVEN8IS (Weller) 



Plate 19, figures 1-2 



1914. Echmoconchus genevievensis Weller, Illinois Geological Survey, mono- 

 graph 1, pages 140-141, plate 18, figures 1-6. 



The collection contains a few poorly preserved specimens of a Pustula 

 that resemble ''Echinoconchus" genevievensis of Weller. The specimens 



