1. _Orthocerata_ (plates, fig. 463 to 470), containing the genera Belemnites, Orthoceras, Nodosaria, Hippurites, and Conilites. Hippurites certainly has no affinity with the Cephalopoda, but is ascertained to be a bivalve shell, properly belonging to the family Rudistes; the other genera are straight, elongated, and conical. 2. _Lituacea_ (plates, fig. 471), containing the genera Spirula, Spirulina, and Lituola, the two latter of which are microscopic. 3. _Cristacea_, containing the microscopic genera Renulina, Orbiculina, and Cristellaria. 4. _Spherulacea_, containing the microscopic genera Miliola, Gyrogona, and Melonia. 5. _Radiolacea_, containing the microscopic genera Rotalites, Lenticulina, Placentula. 6. _Nautilacea_ (plates, fig. 472 to 476). This family contains the following genera--Discorbites, Siderolites, Polystomella, Vorticialis, Nummulites, and Nautilus; the two latter of which alone are now received in cabinets of shells, the four former belonging to that class of microscopic fossils, now termed Foraminifera; the genus Nummulites, although large, may probably belong to the same class, and perhaps it would have been better to have included the remaining genus, Nautilus, in the next family, from which it differs in having the septa which divides the chambers simple at their edges. 7. _Ammonacea_ (plates, fig. 477 to 484). The edges of the septa of these are all more or less sinuous and complicated. This family contains the following genera, Ammonites, Ammonoceras, Baculites, and Turrilites, the latter of which presents a singular anomaly in having an oblique spire, like that of the order Trachelipoda, while it is divided into chambers by sinuous septa. Order _Monothalamous Cephalopoda_. The only shells included in this order belong to the genera Argonauta (plates, fig. 485), placed here by Lamarck, and Bellerophon (plates, fig. 486 and 487), a fossil genus subsequently added. Order _Heteropoda_. The singular and beautiful transparent shell contained in this order, under the generic name Carinaria, forms a covering to a small portion of an animal, equally remarkable and equally distinct from those of all other orders. The above arrangement, although far from perfect, and requiring numerous modifications, is perhaps liable to as few objections as any other yet proposed, and will certainly be more easily understood by those who have not the opportunity of studying the soft parts of the animal. * * * * * CONCHOLOGICAL MANUAL. ABIDA. Leach. A genus founded on a species of PUPA, which has the peristome slightly reflected, and numerous plaits in the aperture. Pupa Juniperi, Pupa secale, Draparnaud. Great Britain; also Central and Southern Europe.