206 
NAUriLOIDEA. 
^ Prodr. de Paleont. Stratigr. vol. i. p. 245, latidorsatus, d’Orb. Pal. 
Fran 9 ., Terr. Jurass. vol. i. p. 147, pi. xxiv. {not of Schlotheim). 
Nautihis robustus. ~a, lateral view, showing the cast of part of the body- 
chamber, the test being present in the septate part of the shell, where a few 
lines of growth are indicated ; b, front view. Drawn from a specimen in 
the British Mu.seum (No. 37010). Rather less than one third natural 
size. 
inch ; the last two septa are only three quarters of an inch apart 
on the periphery. The siphnncle has not been seen. The body- 
chamber occupies at lea.st one half of the last whorl. The test is 
very thick and its surface smooth, or marked only with lines of 
growth, as seen on fig. 38, a. 
Bemarl:s. “ There are three examples of this fine species in the 
British Museum Collection, two of which are adult shells and the 
other in the adolescent stage of growth. The largest specimen 
(the figured one) measures about 8 inches in its greatest diameter 
and about 5| inches in its greatest width. 
“ This species is mostneaxly allied Toarcensis^ d‘Orbigny\ 
but is distinguished by its narrower form, more open umbilicus, and 
closer septa. 
“ Not feeling certain that the present species had not already been 
median line of the periphery, where the whorl has a thickness of 
inches ; in the middle of the sides their distance is only half an 
Fig. 38. 
