OASTROPOI'A 

 1 



tScAi.n .:mm-. Shell turbinate, spire only moderately high; whorls flat 



above ri-inn step-like one above the other, sharply angular at the periphery, 

 produced below; no umbilicii-: aperture subtriangular, apparently drawn out below; 

 columellar lip rather tliick. ^lightly twisted. Surface markings and form of outer 

 lip unknown; probably as in Omospira and /////./MX/OW/I. Type, S.angulatus Eramons. 



4. Sealita angulattui Eiiini..n-, Chazy limestone, Cha/y, New York. View of a weatli. r.-,| 

 specimen. Imbedded In stone, (bowing part f th<> -;p|.-r whorls In section and the uuiblllcal legion and 

 ly twisted columellar lip. Received from }'rt. H. M. Sn-l.-y and now In the collection of E. O. 

 h. 



The accompanying figure shows nearly all we could learn of this genus and 

 specif-. The general form reminds one of certain species of Ijophospira, but we are 

 certain that the angular periphery of the whorls does not carry a band as in that 

 genus. Unfortunately, neither the original types nor, so far as known, any of the 

 specimens discovered since, afford any positive knowledge concerning the form of 

 the outer lip and surface markings. Although we believe that these characters will 

 prove to be essentially as in the preceding genera of this family, we must admit that 

 the question i- complicated by the marked resemblance which S. anyululus\)ea.n to 

 ''ifi/'inn. For the present then the name Scalitcs should be restricted to 

 the species to which it was originally applied. 



Of these five genera Euomphnlnpt'-ru* is the most recent, being perhaps entirely 

 an I pper Silurian type. The others with a few doubtful exceptions, are confined 

 to Ixjwer Silurian deposits. Hnjilii-tinna begins with several species in the Chazy 

 and continues to the top of the Cincinnati period; Ifapliistntiiiint is known in the 

 Trenton, Hlack River and Calciferous formations, and we have reason to believe 

 that the type reaches as far back as the Cambrian: while 0m<wp/>' comprises Hlack 

 River and Trenton species and perhaps a single Cpper Silurian form. i:<i]>liist<miina 

 strikes us as the mo-t primitive of the four Lower Silurian types and we feel 

 reasonably satisfied that the others were evolved from it. llujtliixinm-t was prod 

 by flattening the spire, and by the anterior prolongation of the central portion of 

 the lower lip, the latter modification cauMii;.' the hook of ltni>liixf<itnin>i to l>e replaced 

 by a notch in the upper side of the outer angle of the aperture. Btiomphalopt 

 differs chiefly in its more rounded volutions, and c "ly develop! carina. The 



