OF FOSSIL MULTILOCULAK SHELLS. 417 



and nautilus. According to Count Minister, the species from the 

 P'iclitelgebirge admit of the following description : — The narrow siphunele 

 is constantly found on the ventral part of tiie spiral shell, where it 

 passes through a succession of small funnel-shaped apertures in the 

 chambers. The whorls of the spire are free, never entirely enveloping 

 the inner ones ; and the last, and part of the last but one, of the 

 turns have no septa. The intersections of the septa with the shell 

 form undulations, or simple lateral lobes, at oblique angles, and dorsal 

 and lateral rounded saddles* ; but the line of intersection is not den- 

 ticulated as in goniatites, or marked in the more intricate lines which 

 characterise the ammonite. The siphunele not being generally visible, 

 it is by means of the dorsal saddle that this new genus is distinguished 

 from goniatite, which always has a dorsal lobe on the medial line of 

 the back. Count Miinster elsewhere observes, that it is so difficult to 

 obtain specimens having the septa apparent, that without extreme care 

 it is almost impossible to avoid error ; and that it is still more rare 

 to find the siphunele visible, since in the new genus, as well as in 

 goniatites, it is so slender and so close to the shell as to be usually 

 invisible, even when the marble in which it is found is polished. 



Now the condition of the Cornish specimens I have examined is 

 very different from that of the German ones, and much more perfect 

 in some respects than these seem to have been ; but there are many 

 points in the above description which do not at all agree with my 

 observations. One of the most important of these is the nature of 

 the siphunele, which seems to be obscure in Count Miinster's species, 

 but is very prominent and easily seen in those which I have made 

 out. But it is not only easily seen — it is decidedly large ; and al- 

 though near the shell cannot possibly be overlooked. In one species tiie 

 diameter of the aperture in the septum is one-fifth of the extreme 

 length of the septum ; a proportion much larger than is commonly 

 found in any species of nautilus, and which indeed is only paralleled in a 



* The word saddle is here used to denote those separations between the lobes upon which 

 the mantle of the animal is suppo.sed to have rested. Dr Buckland has explained the lan- 

 guage introduced by Von Buch on this subject, in a note, page 'SaS, of his Bridgewater 

 Treatise, to wliich I must refer for a more complete explanation. 



