[NVERTEBRATE PALAEONTOLOGY. 277 



vex, and its umbilical region less impressed.. It is in most respects, except- 

 ing size, however, more similar to our Haminea subcylindrica, bul is much 

 smaller, less nearly cylindrical, and differs in the presence of the fold at the 

 base of the columella, while it is proportionally a decidedly thicker shell. 



Locality and position. — Morean River; from the Fox Hills group of the 

 Upper Missouri Cretaceous series. 



ACT/EONIDiE.* 

 Genus ACTJEON, Montfort. 



Synon.— Acicmn, Montfort I 1810), Couch. Syst.. II, 314.— Cuvier (1817), Regne An.— Conrad (1830), Jonr. 

 Acad. Nat, Soi. Philad., VI, 226; Proceed. Acad. X. S. ( L862), XIV, 570, and Ani. Jour. 

 Couch. (1865), I. 34— D'Orbigny | L842), Paleont. Fr. Terr. Cr<5t., II, 1-23.— H. and- A. 

 Adams (1854), Genera Recent Moll., II, 4.— Meek and Hayden (1856), Proceed. Acad. 

 Nat. Sci. Philad., VIII. 63; and (1858) J*6.,X, 54.— Meek (1864), Smithsonian Cheek-List 

 X. Am. Cret. Fossils, 17.— Gabb (1864), Palseout. Cal.,1,142; and (1869) i&., II, 115 and 

 •232.— Stoliczka (1868), Pahcont. Indiea, II. 402: and of many others (not of Oken, 

 18i:. i. 



Tornattlla. Lamarck (1812), Extr. d'un Cours, 117; and (1822) Hist., VI, 219.— Fe"russ. (1819), 

 Prodi.. 119 : and (1921) Tab. Syst., xxxiii.— Goldf. (1820), ZooJ., 657.— Blaiuv. (1824), 

 Diet. Sci. Nat., XXXII, 245.— Desh. (1832), Encyc. Meth.. Ill, 1H41 ; and (1864) Descr. 

 An. sans Vertebres Bassiu Paris, II, 592.— Pbilippi (1836), Moll. Sic, 166.— Sowerby, 

 jr. (1839), Conch. Man.. 106.— Adams (1840), Bost. Soc. N. Hist., Ill, 323.— Gray (1842), 

 Synon. Brit. Mils., 90.— Forbes and Hanley (1853), Hist. Brit. Moll., Ill, 523.— Chenu 

 (1859), Man. Conch., II, 385.— Gould and Binuey (1870), Iuv. Mass. (2d ed.), 224.— Tryon 

 (1873), Am. Marine Conch.. 99. 



Kjinilla, Silvertro]) (1833),Edingb.Ne\v Philos. Join., XV. 



Myosola, Gray (1847), Proc. Zool. Soc-., 160. 



Etym. — 'Ajcraiav, a mythological name. 

 Type. — Voluta tornatilis, Linn. 



Shell subovate, thin, spirally striated or puncto-striate ; spire moderately 

 produced, but shorter than the body-volution; aperture rather narrow, long, 

 acute behind, and rounded and entire below; lip thin ; columella provided 

 with one oblique fold. 



The genus Actceon is very closely related to Solidula, Fischer: so closely, 

 indeed, as to lead some high authorities to unite them; while others treat 

 them as two distinct genera. About the only differences that can be pointed 

 out are the greater thinness of the shell, and the presence of only one fold 

 on the columella in Actceon; while Solidula has two folds and a thick shell. 

 It is quite possible that these may be only subgeneric characters; and, if this 

 conclusion should lie established, it will be necessary to use Fischer's name 

 Solidula for the genus, as it has priority of date over Actceon. Among fossil 

 species, we find some with three folds on the columella; bul these generally 



* See note at the end of this description of the genus Actceon. 



