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and nautilus. According to Count Münster, the species from the Fichtelgebirge admit of the following description:-The narrow siphuncle is constantly found on the ventral part of the 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 denticulated as in goniatites, or marked in the more intricate lines which characterise the ammonite. The siphuncle 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 Münster 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 siphuncle 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 siphuncle, which seems to be obscure in Count Münster'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 although near the shell cannot possibly be overlooked. In one species the 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 supposed to have rested. Dr Buckland has explained the language introduced by Von Buch on this subject, in a note, page 353, of his Bridgewater Treatise, to which I must refer for a more complete explanation.

few species of orthoceratites. If then, as there seems every reason to suppose, the siphuncle is the most important character in the shells of multilocular cephalopods, this very great difference would of itself warrant the formation of a separate group. All the species from Cornwall are provided with decidedly large apertures in the chambers, and in all, these funnel-shaped tubes are easily seen, produced beyond the septum about half way into the next chamber.

But again, the markings on the shell which seem so useful in determining Count Münster with regard to any doubtful cases, are in our English species apparently not to be depended on. Our fossils are in beautiful condition; the actual shell certainly remains in one specimen at least, and we can trace a succession of transverse striæ marked with great beauty and regularity upon it; but although the casts of the chambers may be separately examined, the nature and use of the lobes does not quite appear. One thing is certain, they do not correspond to the intersection of the septa and the shell, and in only one of three species do they occur at all. Some idea of the form of a septum will be obtained from Fig. 4, Plate VIII. which represents a side and front view of the cast of a chamber belonging to a species not determined.

-a

The technical description of the genus will be thus expressed :—a discoid spiral multilocular shell; sides nearly simple; whorls contiguous, the last not enveloping the rest. Septa transverse, numerous, concave outwardly, and perforated on the ventral margin for a siphuncle.

In order to determine the place of this genus among other shells of cephalopods, it will be necessary to pay most attention to goniatite and nautilus, as it is to these that the nearest approximation is made. Von 'Buch gives as the character of the former group, the dorsal siphuncle of the ammonite, comparatively small and delicate; the lobes of the septa completely deprived of lateral denticulations, and the striæ of growth resembling those of nautilus, in not being directed forwards, as in ammonites, but reflected backwards. The nautilus is known by its usually central and comparatively large siphuncle, and the greater or less envelopement of the whorls of the spire by the last one formed.

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The new genus Endosiphonites differs from goniatites and nautilus in the position of the siphuncle, and it agrees with both in the direction of the striæ of growth. The whorls, though contiguous, never envelope; and the septa seem usually very nearly simple. Taking D'Orbigny's classification, which being founded chiefly on the position of the siphuncle, must be preferred, we refer this genus to the family Nautilacea, and place it between Nautilus and Lituite.

We come now to consider the species, and the English localities not having been searched with a view to the discovery of these fossils, we have at present only three sufficiently well defined to admit of description. These are figured in Plate VIII. and I have named them as follows:

(1). Endosiphonites Münsteri nob. PLATE VIII., Fig. 1. This being the largest species, I have named it in honour of the first discoverer of the genus. The individual figured is an extremely beautiful fossil, and, as will be seen from the figure, shows the siphuncle very clearly. It is partially burnt, having been obtained by the fracture of a lump which had passed through a kiln without being reduced to a calx; so that most of the striæ of growth are destroyed, although I have no doubt they were before the burning sufficiently clear. It is the only species in which there are decided lobes, and is remarkable for the very large size of the last whorl, the area of the aperture being more than five times as large as that of the corresponding chamber in the former whorl. It is also very flat, the length of the aperture being more than twice its width, and this without any appearance of the shell having been injured or crushed. It measures four inches across.

(2). E. carinatus nob. PLATE VIII., Fig. 2. This species is remarkable for its elliptical form, and for having a keel running along the dorsal margin. Its dimensions are fourteen-tenths by nine-tenths of an inch. It is marked by a series of fine but beautifully distinct striæ, which may be clearly seen in some parts of the specimen figured, where in all probability the original shell remains. This is the species alluded to above as having a very large siphuncle, seen in the figure at (a).

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