CLASS FIRST. 

 UNIVALVE TESTACEOUS MOLLUSC A. 



Order I. — CEPHALOPODA. 



Head of the animal emanating from a bag-shaped 

 mantle, and surrounded by inarticulated arms, provided 

 with a sucker, and investing the mouth ; two sessile 

 eyes ; mouth furnished with two horny mandibles : pro- 

 vided with three hearts ; the sexes in different indivi- 

 duals. 



Division I. — Cephalopoda Polythalama. 



Shell multilocular, partly or entirely internal, and 

 placed in the posterior part of the body. 



In the arrangement of Lamarck, this is the third 

 division of the Cephalopoda. The first embraces the 

 Sepia, or Cuttle Fish, which does not properly rank with 

 the Testaceous Mollusca, and the second the Argotumta, 

 or Paper Nautilus, of which genus no fossil species have 

 yet been discovered. 



Fajiily \. — Nautilacea. 



Shell discoid, spiral, multilocular, with simple parti- 

 tions ; volutions contiguous, the last or the body one 

 enveloping the rest; the septa transverse, and externally 

 concave, perforated in the disk ; margins entire. 



Genus L— BACULITES.— ZamarcA. 



Univalve, straight, lanceolate, part of which is inter- 

 nally divided by septa, or partitions, with sinuated edges ; 

 the septa are penetrated by a siphuncle near their anterior 

 margins. 



1. B. Faujasii. — Fauja's Baculite, pi. I. fig. 1. 

 Lamarck An- San Vert, VII. p. 647; Sowerby, Mineral 



Conchology, VI. p. 186, pi. 592, fig. 1 ; Fauja's Hist. Nat. 

 de la Mont, de St Pierre, p. 140, pi. 21. fig. 2, 3. Brown 

 in Popular Encj'eloptedia, V. p. 335, pi. 65. fig. 1. Brown's 

 Elements of Fossil Conchology, pi. II. fig. 1. 



Smooth, both edges equally rounded, and the sides slightly 

 compressed. 



Found in the chalk at Norwich, by C. B. Rose, Esq. and 

 has occurred also at Hamsey. 



2. B. Obliquatus. — -The Oblique Baculite, pi. I. fig. 6. 

 Sowerby, VI. p. 186, pi. 592. fig. 2, 3 ; Hamites bacu- 



loides, Mantell, Geology of Sussex, p. 123, pi. 2.3. fig. 6, 7. 

 Do. Geolog}' South East of England, pi. 160. fig. I. 



With a very obliquely undulated and annular surface ; the 

 annulations deepest at the margins, or at that place where 

 the siphuncle is situate. 



Fig. 7 represents a rare variety, wherein the aperture is 

 placed obliquely ; each side is provided with a large oval 

 reflected lobe. The aperture is marked by a, and the situation 

 of the siphuncle by S. 



This species is very common in the Gray Chalk Marie of 

 Lewes, and abundant at Hamsey. Mr Mantell remarks, that 



" this species may easily be recognized by its extraordinary 

 length, by the smoothness of its surface, and the great obli- 

 quity of the few undulations with which it is ornamented. 

 Fragments from one to six inches in length, and about 0.4 

 inch in diameter, marked with oblique undulations, and occa- 

 sionally exhibiting foliaceous septa, are very abundant in 

 every locality of the Gray Marl near Lewes." 



All the species, whether Foreign or British, which have 

 yet been discovered, occur in the lower beds of Chalk or 

 Chalk Marie, and in the upper Green sand. 



Genus II.— HAMITES.— ParAmson. 



Shell fusiform ; hooked or bent into two parallel limbs ; 

 chambered ; septa undulated at their margins, with a 

 siphuncle at their outer edge. 



1. H. GiGAs. — The Giant Hamite, pi. I. fig. 13. 

 Sowerby, Min. Conch. VI. p. 188, pi. 593, fig. 2. 

 Abruptly curved, with large, transverse, nodulous, oblique 



ribs, the tubercles on each being generally six, which are 

 laterallj- expanded ; on both sides are three obtuse spines, 

 united to form each rib, which becomes almost obsolete as 

 it passes over the front ; the larger spines are placed near the 

 front : section, hexagonal, protruding in front, with the sides 

 and back concave. Size, from aperture to the extreme edge 

 of the curve, 6i inches ; greatest thickness, 2^ inches. 



Found by G. E. Smith, Esq. in the second or lower bed of 

 limestone, in its uppermost course of Rag and Clay, near 

 Seabrooke, between Sandgate and Hythe, and on the Roughs, 

 west of Hythe. 



2. H. GRAND IS The Great Hamite, pi. I. fig. 9. 



Sowerby, Min. Conch. VI. p. 187, pi. 593, fig. 1. 

 Surface, with numerous shallow oblique undulations in 



front ; each side provided with a few short oblique ribs, 

 which are largest at their extremities ; between each rib are 

 six somewhat produced, rounded furrows, reaching to the 

 line beneath which the siphuncle is situate ; posterior surface 

 smooth ; margins of the septa formed into six extremely acute, 

 numerous, and complex sinuses, arranged into six very unequal 

 lobes ; section sub-rotund. 



Found in the parish of Smeeth, near Hythe, on the estate 

 of E. Hughes, Esq. in a quarry of Kentish Ragstone. 



3. H. PLicATiLis. — The Folded Hamite, pi. II. fig. 10. 

 Sowerby, Min. Conch. III. p. 59, pi. 234, fig. 1. Mantell, 



Geology of Sussex, p. 121, pi. 23, fig. 1, 2. 



Shell somewhat compressed, with numerous, regular, an- 

 nular, continuous, and undivided ridges ; each side provided 

 with two rows of depressed equal tubercles, which extend 

 over those of the annular ridges ; with two ridges between 

 each tubercle ; curvature gradual. 



Found in the chalk marie at Bishopstrow, near Warminster 



4. H. uNDULATUs The Waved Hamite, pi. II. fig. 11- 



Hamites armatus, Sowerby, Min. Conch. III. p. 59, pi. 234 



fig. 2. 



Depressed, with irregular transverse undulations ; two rows 



