80 THE NAUTILUS. 



As to the place of origin of Strobilops we have no reliable data. 

 The presence of typical forms of the genus in the Eocene shows that 

 the group is a very old one, evolved in the Mesozoic. It is, more- 

 over, strikingly distinct from all other genera, and wonderfully con- 

 servative in general morphology. Until information from Mesozoic 

 strata comes to hand, we can only surmise with some probability that 

 Strobilops arose somewhere in the northern hemisphere. It probably 

 overran the entire Holarctic realm a long time ago, pushing south- 

 ward into the Oriental region and the American tropics at a time 

 remote enough to permit the evolution of strongly marked species in 

 these areas. 



ANOTHEB LARGE MIOCENE 8CALA, 



BY W. H. DALL. 



Mr. W. W. Atwood of the U. S. Geological Survey has been 

 making a study of the Miocene strata of Alaska Peninsula and the 

 Shumagin Islands during the past summer, and collected a number 

 of interesting fossils. Among these is a specimen of a species of 

 Scala, or Epitonium, belonging to the group of giant Scalidae which 

 is so characteristic of the Miocene of Oregon and some other parts of 

 the Pacific coast. The list comprised the following species already 

 described and figured. 



Opalia rugifera Dall, 



Arctoscala condoni Dall, 



Catenoscala oregonensis Dall ; 



together with the species about to be described. The type of Arcto- 

 scalu is A. greenlnndica Perry, a recent species. Opalia rugifera is 

 a member of the group represented in the San Diego Pliocene by 

 0. varicostata Stearns, and in the recent fauna by 0. borealis Gould. 

 Catenoscala is a new group in which the anterior third of the whorl 

 is covered with a thick layer of enamel. 



Epitonium (Acrilla) atwoodi n. sp. 



Shell large, with rotund whorls rapidly increasing in size ; sur- 

 face covered with a low reticulate sculpture comprising low axial 

 lamellae, about 1.5 mm. apart on the periphery of the whorls, slightly 



