FUSID^. 131 



MESORHYTis, Meek. Shell agreeing nearly with Peistocheilus 

 in form, but with plaits of columella stronger, comparatively 

 little oblique, and exposed directly opposite the middle of the 

 aperture ; surface with fine spiral strias, and vertical costse. F. 

 gracilenta, Meek (xlviii, 88). Cretaceous ; Yellowstone River, 

 150 miles from its mouth. Has the folds of a Mitra, rather than 

 a Fasciolaria, and Meek refers it with considerable doubt to its 

 present position. 



CRTPTORHYTis, Meek. Shell generally under medium size, with 

 volutions convex, but constricted above, and provided with 

 regular vertical costse or small folds ; plaits of the columella 

 very oblique, not exposed in a direct view into the aperture, and 

 occupying a higher position than in the typical group ; outer lip 

 smooth within. F. Cheyennensis, Meek and Hayden (xlviii, "89, 

 from a cast). Cretaceous ; Dakotah. 



LIROSOMA, Conrad. Subpyriform; ribbed, beak narrow and 

 produced, slightly recurved ; one long, very oblique plait at the 

 angle of the columella. F. sulcosa, Conrad (xlviii, 90). Miocene ; 

 Maryland. 



FASCiOLiNA, Conrad. Fusiform ; columella nearly straight to 

 the extremity of the beak ; one prominent oblique fold on the 

 columella, situated above the middle of the aperture. F. Woodii, 

 Grabb. Miocene ; New Jersey. The only figure does not exhibit 

 the aperture, but Conrad states that the fold is situated more 

 remote from the beak than in any other genus except Cuma. 



SvBFAMiLY FTYGHATBAGTIN^. 



This group was distinguished as a family by Stimpson. The 

 shell of Ptychatractus unites the form of a Sipho with the folds 

 of a Fasciolaria; its small size, color, and northern habitat 

 will distinguish it from the latter, even without taking into 

 account the very diverse dentition ; j^et without the latter differ- 

 ence it would scarcely have been advisable to have separated 

 the single species upon which the genus was founded from 

 Fasciolaria. 



Ptychatractus, Stimpson, 1865. 

 Distr. — 3 sp. Boreal Atlantic and Pacific. P. ligatus, 

 Mighels and Ads. (xlviii, 91). 



Shell fusiform, spirall}^ striated ; aperture with a moderate 

 canal ; columella plicated as in Fasciolaria. 



Meyerta, Dunker and Metzger. 

 Syn. — Metzgeria, Norman. 



Distr. — M. alba, JeflTreys (xlviii, 92). Faroe Is., jSTorth Sea, 

 Norway. 



Shell elongate-fusiform, longitudinally obtusely plicate ; spire 



