NO. 2217. THE GENUS EPITONIVM AND ITS ALLIES— PALL. 473 



Opalia varicostata Stearns, 1875 (not of Sacco, 1890), of the San 

 Diego Pliocene, is a large species with 10 or 11 ribs sometimes partly 

 obsolete. 0. varicicostata Cossmann, 1912, is synonymous. The 0. 

 anomala of Stearns, 1875, is practically without varices except near 

 the tip of the spire, where traces may sometimes be found. It is 

 an Opalia and not a Crassiscala, as supposed by De Boury. Tho 

 Miocene Catenoscala orcgonensis Dall, 1900, is accompanied by a 

 largo Boreoscala condoni Dall, and an Opalia of the varicostata typo 

 which I called 0. ru.gifera. These large P^pitoniums seem to be rather 

 characteristic of the Northwest Coast Miocene. 



A somewhat degenerate representative of the Opalia group is B. 

 pluricosfata, new species, ranging from Forrester Island, Alaska, to 

 San Diego. It resembles the ribbed upper portion of 0. wrollew- 

 sJcii a good deal, but is smaller and more cylindrical, with eight vari- 

 ces. It has seven whorls without the nucleus, the varices are con- 

 tinuous up the spire, the interspaces smooth, the basal disk octohe- 

 dral from the intersection of the ribs, somewhat concave, and rela- 

 tively smaller than in wrohlewskii. Length, 16; diameter, 5 mm. 

 U. S. Nat. Mus. Cat. No. 56054. The type-specimen is from Neeah 

 Bay, Washington. 



Another group referred by Carpenter to Opalia is separated by De 

 Boury under the name of Dentiscala. Representatives of this type 

 are D. crenatoidcs Carpenter, 1864, from the Gulf of California, rather 

 small with a coarse spiral rib on the basal disk and deep pits at the 

 intersections of the nine axial ribs. A species wliich has generally 

 been confused with this and is much more common, is D. crenimar- 

 ginata, new species, which ranges from Monterey, California, to 

 Puerto Libertad, Mexico. It is larger, much stouter, spirally stri- 

 ated, with a convex smooth basal disk, the 12 axial ribs on the last 

 two whorls obsolete on the sides of the whorls but coronating the 

 suture. It has 6 or 7 whorls without the nucleus, the varix at the 

 aperture is heavy, and there is sometimes another heavy varix indi- 

 cating a resting stage. Length, 16; diameter, 7 mm. U. S. Nat. 

 Mus. Cat. No. 111207. The type-specimen comes from La Paz. A 

 species somewhat intermediate between the two above noted, D. 

 inscnlpta Carpenter, 1864, is found in the Pleistocene of Snnta 

 Barbara, California, but it is without the fine spiral surface sculpture. 



A smaller species, D. nesiotica Dall, was dredged by me in 16 fath- 

 oms at Catahna Island. It has 12 varices, rather feebly carried over 

 the whorl and obsolete on the basal disk. Sharp spiral sculpture 

 covers the surface and the terminal varix is heavy; there are six 

 whorls, not including a smooth nucleus of a whorl and a half; the 

 suture is markedly coronated by the ribs. Length, 10.5; diameter, 

 5 mm. U. S. Nat. Mus. Cat. No. 56900. 



