Ko.liiiO. PROCEEDINGS OF THE NATIONAL MUSEUM. 713 



Specitic name in honor of Doctor A. C. Peale, who collected the type 

 specimen. 



Formation and locality. — Middle Cambrian, Flathead Terrane. Xortli 

 of East Gallatin Kiver, north of Hillsdale, ^Fonlana. Also, on the east 

 side of Gallatin Kiver above Gallatin City. (J^o. 2G430, 17.S.X.M.) 



IPHIDEA CRENISTRIA, new species. 

 (Plate LIX, ligs. 4, 4a, 4&.) 



Pedicle valve subconical, beak nearly apical, curving slightly over to 

 the psendodeltidiuin. False area very narrow, separated from the 

 curvature of the shell by being turned somewhat abruptly backward. 

 Pseudodeltidium comparatively broad, but decidedly short as compared 

 with thnt of I. hella or 7. fiupcrha. It is more of the tyi)e of /. lahrulor- 

 im. It is strongly arched, leaving a broad, high space between it and 

 the plane of the shell. 



Dorsal (brachial) valve unknown. Surface of ventral (pedicle) valve 

 marked by very fine, slightly crenulated stria* that are so crowded on 

 the false area that they are nearly lost, and only one or two varices of 

 growth and a few strine are shown on the pseudodeltidium. No traces 

 of an embryonic; foramen are seen, save the slight slit at the apex of 

 the shell. 



This species is clearly distinguishable from other described forms of 

 the genus by its highly arched pseudodeltidium and crenulated surface 

 striic. 



Formation and locality. — Middle Cambrian, Tonto Terrane. In thin 

 intercalated limestone layers near head of Nuukoweap Valley, Grand 

 Canyon of the Colorado. (No. 20431, U.iS.N.M.) 



IPHIDEA ALABAMAENSIS, new species. 



(PlateLIX, fif^s. 5, 5rt.) 



In following the Lower Cambrian rocks southward from Vermont, the 

 first type of Iphidea met with is /. stissingensis, which occurs in the Mid- 

 dle Cambrian of Dutchess County, New York. This is fairly well dis- 

 tinguished by its surface characters from I. lahradorica and its variety 

 sicantonensis, but at the next locality to the south, in eastern Tennessee, 

 four miles north of Eogersville, in the Ivogersville shale of the Middle 

 Cambrian, w;)S found a form that is practically identical with the north- 

 ern species or its varietj^, as far as it is possible to compare specimens 

 preserved in limestone with those preserved in shale. The same form 

 also occurs in the Middle Cambrian shales of the Cowan Creek section, 

 Cherokee County, Alabama. There is, however, a difference in the sur- 

 face stria' that distinguishes it from 7. lahradorica and its variety and 7. 

 stissi)i(jen.sis. It is the tendency to crenulation of the stria' in nearly 

 all the specimens that have been examined. This in extreme cases 

 goes so far as to approach the surface, so characteristic of 7. pannula. 



