32 



MOLLUSCA. 



Nautilus. 



duce an undulated appearance in its edges ; the aperture is 

 long, and faces the spiral part. 



Found in the Gray Chalk Marie at Hamsey, and is very 

 rare. 



3. S. EQUALis.— The Equal Scaphite, pi. XXII. fig. 7, 8, 

 9, and 15. 



Scajyhites equalis. Sowerby, Min. Conch. I. p. 53, pi. 18, 

 fig. 1, 2, 3. Fleming, Brit. An. p. 249. Buckland, Geology 

 and Mineralogy Considered, II. p. 66, pi. 44, fig. 15, 16. 



Involute, umbilicate ; inner volutions concealed ; inner 

 parts of the sides with projecting distant ribs ; these extend 

 to nearly the centre, where they are rounded ; smaller ribs 

 equal to two to each of the larger ribs; these pass over the 

 greatly enlarged ventricose, and thickened ambit ; aperture 

 incurved ; the outer coating preserves part of the pearlaceous 

 lustre of the original shell. Length about an inch. 



Fig. 7, side view ; 9, a transverse section of the 

 portions, exhibiting the arrangement of the lobes and saddles ; 

 from which it will be observed they are the same as in the 

 genus Ammonites, the siphuncle also is seen on the dorsal 

 marg'.n at a ; 8 exhibits the front, with the volution central ; 

 15 is a section through one of the concanierations, exhibiting 

 part of the undulations. 



Found in the Green Sand, at Yeovil, by Dr Leach. 



4. S. OBLiQuus. — The Oblique Scaphite, pi. XXII. fig. 10, 

 11, 12, 13. 



Scaphites ohliquus. Sowerby, Min. Conch. I. p. 54, pi. 18, 

 fig. 4, 5, 6, 7. Fleming, Brit. An. p. 249. 



Obliquely involute ; umbilicate ; inner volutions concealed; 

 sides transversely striate, which, after reaching the centre, 

 become doubly or triply furcate, and pass over the rounded 

 ambit, and meet with those on the opposite side. Length 

 nearly an inch ; width about three quarters, thickest part half 

 an inch. 



Miss Bennet possesses a specimen from the Hard Chalk, 

 Warminster, which measures an inch and a quarter in 

 length. 



This shell will readily be distinguished by the obliquity of 

 its curve, the fineness of its striae, and the great incurvation 

 of the last volution. 



Found in the Marie Pit, Lewis, Hamsey, by Dr Mantell, 

 and is not met with in the Chalk at Brighton. 



Fig. 12 exhibits the obliquity of the spire in a front view of 

 the shell; fig. 13 is a segment shewing the concamerations. 



5. S. TUBERCULATUs. — The Tuberculated Scaphite, pi. 

 XXIl.fig. 6and 14. 



Scaphites tuherculatus. Parkinson, Organic Remains, III. 

 p. 145, pi. 10, fig. 10, 11. 



Involute, umbilicate ; inner volutions concealed ; from the 

 inner margin a series of wide set ribs emanate, the six outer 

 ones, on reaching the centre, terminate in a large and pro- 

 duced tubercle, and are met by numerous small rounded ribs, 

 which pass over the ambit ; in the remaining portion of the 

 volution, the large ribs cross the sides entirely, and passing 

 over the somewhat rounded ambit, proceed continuously to 

 the inner margins on the opposite side ; numerous small 

 round ribs intervene between these, and terminate about the 

 centre of the sides ; at the termination of the reflected part at 

 the mouth, a border is formed by the edge of a regularly 

 rounded groove. Length an inch. 



Found in Dorsetshire, as also in the Chalk Pit, Brighton, 

 by Mr Herbert. 



Family II. — Nautilacea. 



Shell discoidal, with a central spire, and short cells, 

 which do not extend from the centre to the circum- 

 ference. 



Genus VII.— NAUTILUS.— Z.m««MS. 



Sliell suborbicular, multilocular ; convolute, with con- 

 tiguous volutions, and simple partitions; septa transverse ; 

 and externally concave, perforated in the disk ; margins 

 entire ; aperture ample. 



1. N. TETRAGONis The Quadrangular Nautilus, pi. XXII. 



. 16. 



Nautilus tetragonis. Phillips, Geology of Yorkshire, II. 



fig. 16 



Discoidal, flattened, with tetragonal volutions ; ambit 

 slightly concave, and provided with a small spiral ridge 

 within the angles, sides crossed by sharp bent stria;, which 

 rise into ridges, or plaits on the edges ; septa outwardly con- 

 cave. 



Found at Kulkeagh and BoUand, Queen's County, Ireland ; 

 and also in Northumberland. 



2. N. iNEQUALis. — The Unequal Nautilus, pi. XXII. 

 fig. 17. 



Nautilus inequalis. Sowerby, Min. Conch. I. p. 88, pi. 

 40, lower figures. Fleming, Brit. An. p. 229. 



Spheroidal, umbilicate ; aperture nearly round, and 

 obscurely trilobate, embracing the volutions, and nearly 

 equal to one-half the diameter of the shell in length, and 

 about the same in width ; septa but slightly curved, remote 

 in the inner volutions, and in the outer ones rather con- 

 tiguous ; siphunculus situate near the inner margin of the 

 septum. 



It is rather singular that the septa should be closer in the 

 outer volutions than in the inner ones, where the distance is 

 equal to their own length. 



Found at Folkstone by Mr Gibbs. 



3. N. MULTicARiNATUS. — The Many-Keeled Nautilus, pi. 

 XXII. fig. 18. 



Nautilus tnulticarinatus. Sowerby, Min. Conch. V. p. 

 129, pi. 482, fig. 1, 2. Phillips, Geology of Yorkshire, IL 

 p. 232. 



Discoidal, subglobose, umbilicate ; umbilicus large, deep, 

 and angular, witii an angular edge, in which the sides 

 of the inner volutions are half exposed ; ambit compressed, 

 very broad, and flattened, with its centre plain, and provided 

 on each side with four sharp carinse, exclusive of the one 

 which invests the margins of the umbilicus. 



Found in the Black Rock, at Cork, Ireland, where it is 

 very rare. 



4. N. CARiNiFEKUs The Keeled Ammonite, pi. XXII. 



fig. 19. 



Nautilus cariniferus. Sowerby, Min. Conch. V. p. 130, 

 pi. 182, fig. 3. 4. Phillips, Geology of Yorkshire, IL p. 232, 

 ph 17, fig. 19. 



Discoidal, subglobose, umbilicate ; inner volutions half 

 exposed within the ver}' large, deep, and sharp margined 



