INTRODTJCTION. Vll 
3. Ltxmgati. — Without either longitudiDal or transverse stri[e in 
the adult. Ex. jS'autihis laticlorsatus, d'Orb. ( = W. Toar- 
censis, d’Orb.), X. inornatus, d’Orb., X tnincatus, J. Sow., 
X. eaxavatus, J. de C. Sow., X. lineatus, J. Sow., &c., 
of the Jurassic rocks, and X. Bouchardiamis, d’Orb., 
X. Clementinus, d’Orb., X. suhlcevigatus, d’Orb., of the 
Cretaceous. 
These divisions are eminently artificial, because they do not take 
into account the form of the shell, that of the umbilicus, or the 
position of the siphuncle, all which characters must be reckoned 
with, if a natural classification is aimed at. 
De Koninck, in his work on the Carboniferous fossils of Belgium \ 
makes the following divisions : — 
1. Glohosi {= Epliiigiioceras^ Coelonauiilus, &c.). — Including Xau- 
tilus hilohaius, J. Sow., X. glohatus, J. Sow., X. crassi- 
venter, de Kon., &c. 
2. Atlantoidei. — Eor Xauiilus Atlantoideus, de Kon., X. neglectus, 
de Kon., &c. 
3. Serpentini (= Coelonautilus, Sohnocheilus^ &c.). — Xaiiiihts Cog- 
anus, d’Orb., X. hiangidatus, J. Sow. (non d'Orbigny), X. 
implicatus, de Kon., X. ingens, de Kon. (non Martin), 
X. pentagonus, J. Sow., X. elephantinus, de Kon., X. don- 
salis, Phill., X. cgclostomus, Phill., tkc. This is the largest 
group, and contains fourteen species. 
4. Tuheradaii (=Solenoch€ilus and Temnocheilus). — Consisting of 
only three species, viz. Nautilus hifrons, do Kon., X. coro- 
natus, M‘Coy, X. latus, Meek and Worthen. 
5. Disciformes ( = Discites, pars). — Nautilus planoter gains, M‘Coy, 
X. difficilis, de Kon., X. trochlea, M‘Coy, X. mutahilis, 
M‘Coy, X. exaratus, de Kon., &c. 
6. Lenticulares { = Phacoceras &c.). — Contains only two species. 
Nautilus oxystomus, Phill., X. complanatusi , J. Sow. 
7. Sidciferi (= Coelonautilus &c.). — Nautilus sulcatus, J. Sow., 
X. Edwardsianus, PhiU., X. suhsulccUus, Phill., X. dis- 
coideus, de Kon. 
8. Cariniferi (= Coelonautilus &c.). — Nautilus cariniferus, J. de C. 
Sow., X. pinguis, de Kon., X. multicar inatus, J. de C. Sow., 
X. Meyerianus, de Kon., &c. 
^ Faune du Calcaire Carbonifere de la Belgique (Annales du Mus. Roy. 
d’Hist. Nat. de Belgique, torn, ii.), 1878, pt. i. p. 90. 
