ACT,.— FXE.] 



GASTROPODA. 



693 



CLASS GASTROPODA. 



The better authors use Gastropoda, and I prefer it to Gasteropoda. The mas- 

 ticatory apparatus or chitinous band, bearing minute teeth and forming a rasp-like 

 ribbon, is called the odontophore, (odous, tooth ; phero, I carry.) When the aperture 

 is round or entire, the shell is called holostomatous, (holos, whole; stoma, mouth;) but 

 when the aperture possesses a notch, more or less prolonged, for the respiratory 

 siphon, or forming a trough-like extension for the skirt of the mantle, as in Fusi- 

 spira, the shell is called siphonostomatous, (siphon, a tube; stoma, mouth.) The 

 margin of the aperture is sometimes called the peristome, (peri, around ; stoma, 

 mouth), or peritreme, (peri, around; trema, an opening.) The notch separating the 

 outer lip from the first whorl is called the posterior canal, and the notch sep- 

 arating it from the end of the columella is the anterior canal. When the 

 columella is solid, it is called imperforate ; and when hollow, perforated. The 

 shells are sometimes composed of aragonite ; at other times there is an inner layer of 

 aragonite and an outer layer of calcite ; and, especially in the younger shells, there 

 is a horny epidermis which may disappear with age. It is said that aragonite is 

 much more readily displaced in fossilization than calcite, which may account for the 

 casts of Murchisonia associated with the shells of Cyclonema, in the same Lower 

 Silurian strata, and other like phenomena in other genera and species of shells. 



The new genus Helenia is supposed to belong to the Dentalidse ; Fusispira 

 should be referred to the Subulitidse ; Metoptoma and Palseacmsea to the Patellidse. 



Euomphalus comes, Hall, syn. for Eccyli- 

 omphalus laxus. 

 flexistriatus and E. maskusi, Whiteaves, 

 1891, Cont. to Can. Pal., vol. 1, pp. 242, 

 243, Devonian, 

 manitobensis, Whiteaves, 1890, Trans. 

 Roy. Soc. Can., vol. 8, p. 100, Devonian, 

 sampsoni, Nettleroth, 1889, Kentucky 

 Fobs. Shells, p. 182, Up. Held. Gr. 



Flemingia, DeKoninck, 1881, Annales du 

 Musee Royal D'Histoire Naturelle de 

 Belgique, tome 6, p. 93. [Ety. proper 

 name.] Shell conical, spire acute, spiral 

 whorls ntarly flat externally; qircum- 

 ference more or less angular ; aperture 

 often depressed, and angular at the 

 outer margin ; peristome not contin- 

 uous, external border oblique, slender, 

 and sharp; columella slender, slightly 

 twisted over, and giving place to the 

 formation of an umbilical fossette more 

 or less large and imperforate ; shell 

 thin ; surface smooth or covered with 

 irregular striae obliquely crossed with 

 more distant lines. Type F. prisca. 

 This genus is nearly related to Eotro* 

 chus. 

 carbonaria, Meek & Worth en, 1866, (Troch- 

 ita (?) carbonaria), Proc. Acad. Nat. Sci., 

 p. 270, Kaskaskia Gr. This species is 

 figured and described by DeKoninck as 



Aclisina bellilineata, S. A. Miller, 1891, 

 17th Rep. Geo. Sur. Did., p. 85, Chou- 

 teau limestone, 

 swallovana, on p. 395, is magnified three 

 and a half diameters. 



Bellerophon gorbyi, S. A.Miller, 1891, 17th 

 Rep. Geo. Sur. Ind., p. 84, Hud. Riv. Gr. 

 incomptus, B. nodocostatus, B. ourayen- 

 sis, B. rugopleurus, B. tenuilineatus, 

 Gurley, 1884, New. Carb. Fobs. Bull. 

 No. 2, pp. 8 to 11, Coal Meas. 

 subcordiformis, Herrick, 1887, Bull. Deni- 

 son Univ., vol. 2, p. 18, Subcarbonif- 

 erous. 



Callonema clarki, Nettleroth, 1889, Ken- 

 tucky Foss. Shells, p. 175, Up. Held. Gr. 



Cakinaropsis deleta and phalera, Sardeson, 

 1892, Bull. Minn. Acad. Nat. Sci., vol. 3, 

 p. 335, Trenton Gr. 



Conchopeltis obtusa, Sardeson, 1892, Bull. 

 Minn. Acad. Nat. Sci., vol. 3, p. 336, 

 Trenton Gr. 



Dentalium granvillense, Herrick, 1888, 

 Bull. Denison Univ., vol. 3, p. 92, Wa- 

 verly Gr. 



Eccyliomphalus perkinsi, "Whitfield, 1890, 

 Bull. Am. Mus. Nat. Hist., vol. 3, p. 30, 

 Calciferous Gr. 

 triangulus, Whitfield, 1890, Bull. Am. 

 Mus. Nat. Hist., vol. 3, p. 29, Calcifer- 

 ous Gr. 



