68 CRETACEOUS GASTROPODA 
This shows, I believe, clearly enough, what reason there exists for the adoption 
of the name and authority of Turris against that of Plewrotoma, and for substitut- 
ing this doubtful and obscure name for one which has been familiar ever since 
naturalists began to look at a shell with a scientific object ;—so much for the names 
Pleurotoma and Turris. 
The number of living and tertiary species of Plewrotoma is very great, but there 
are only few known, which have been described under this name from the cretaceous 
deposits. Excluding the very uncertain species (vide Pictet, Pal. Suiss. 3 me ser. 
pt. II p. 655) the following have to be noticed :— 
1. Pl. subfusiformis, D’Orb., known from the Gosau and from South India ; 
will be described in the following pages. 
9. Pl. fenestrata, Zekeli, (vide Revision, etc., Sitzungsb. Akad. Wien 1865, LIT, 
p. 87) from the Gosau deposits, belongs probably to Clathurella, Carp. (Defrancia, 
Millet.), but is not very certain. 
8. Pl. Heisiana, Miller, from the cretaceous strata near Aachen, a very peculiar 
form, which, so far as the figure admits of a definite opinion, has to be classed with 
Pl. terebralis, Lamarck, Pl. subterebralis, Bell, Pl. dimidiata, Brocchi, and other fossil 
forms. 
To these three European, no less than thirteen American species have to be 
added, viz. :— 
4—16. Pl. araucaria, D’Orbieny, Prodr. II., p. 280; Pl. arata and d’ Orbig- 
nyana, Gabb; Pl. contorta, Meek and Hayden.; Pl. minor, KH. and Shumard, (Gabb’s 
Synopsis, Proc. Amer. Phil. Acad. VIII, p. 145. Lurris) ; Pl. (Lurris) Claytonensis, 
and varicostata, Gabb, (Pal. of California, I. 1864, pp. 92, 93). ‘The first three 
are from Chili, the other four from North America. Further Daphnella ? 
Eufalensis, 7 lintea, ? subfilosa; Drillia distans, novemcostata, ’ Tippana; all spe- 
cies named by Conrad (see Gabb, Synop. Joc. cit. pp. 104, 105), from Alabama and 
Mississippi. 
Mesochilostoma is a doubtful genus proposed by H. Seeley in 1861 (Ann. Mag. 
Nat. Hist. Ser. III., Vol. VII., p. 284) for a species from the upper Greensand of 
Cambridge. The shell is characterized as turreted, with a supposed short canal, and 
on the outer lip with a notch, which forms a keel round the middle of the whorls. 
There are numbers of species known, specially of the czararvzrzym, which have 
these characters perfectly developed. The short description of the species, JZ. striata, 
given by Mr. Seeley, does not add anything more to the knowledge of the genus, 
and it is impossible to form a clear idea of either of them. 
The following species have to be excluded in addition to those quoted by 
Pictet and others: Pl. heptagona, Zekeli, quoted by Pictet, belongs to Pl. subfusifor- 
mis, D’Orb.—Pl. (Turris) involuta, Goldfuss, mentioned by Gabb in his catalogue, 
must be referred to the Vorurm2; and Pl. subspinosa, D’Orb. (ibid.) is Borsonia 
spinosa, Sow. sp. (Stoliczka, Rev. ete. Sitzungsb. Akad. Wien, 1865 Bd. LIT. p. 87.) 
The second known species of Pzevrorouzp2£ with plaited columella is Cordiera 
microptygma (Gabb, Pal. Calif. 1. 93). 
