50 8CALAR1ID.E. 



are t JTeBt Inli:m province appears to be the me- 



lis of the genus; at least more species have been deM-ril>ed 



i that than IVoin any other region. The name indica 



fan< .nee to a ladder; in the vernacular the >hell is 



D afl \\Yii! le-t rap." Tin- synonyms include Sv//,/. 



IK, 17W, and ,S7/^m'////x, 1868; 



psopleura and Scalina, 1805, by Conrad, the three last pro- 

 posed (but no' !'"r American tertiary fossils. 



A number of genera and subgenera have been described. 

 based upon characters of secondary importance, and which can 

 be mostly advantageously reduced to the rank of sections. 



Section SCALARIA (sensu stricto}. 



Whorls a little separated, crossed by regular lamelliform 

 res, umbilicated. Aciona, Leach, 1815, is a synonym. 



:IRUS, Oken, 1815. 



Shell moderately thick, often colored, whorls united, longi- 



;:il ribs usually numerous, aperture suboval, umbilicus 



covered by the left lip. no basal rib. Janthoscala and Turbona 



: . M-'irch, 1876, published without diagnosis, appear to 



include species of this section. 



Section OPALIA, H. and A. Adams, 1 853. 



Shell tnrrieulated, imperforate, whorls united, the last with 

 a basal spiral rib. To this group may be referred J'syrhro&und, 

 Canefri, 1876, and ieihap< Coin/^opleura (Am. tertiary), Conrad, 



Section AMJEA, H. nd A. Adams, 1853. 



Shell turriculated, thin, whorls united. can< ellated, with some 

 thin, irregular varices ; apt-rtnre semilnnar, inner lip gibbous in 

 the middle, outer lip thin, simple. 



Section CIBSOTKKMA, x 



Shell turricnlated, solid, whm-ls cancellated, with i\ few irre-u- 

 ispate varices ; aperture l.,rdci-fd by a thick crenu- 



Section ACIRSA, M -57. 



orll united, varices obsolete; lip thin, 

 simple, Arctic Seas. 



