ORBULITES. CEPHALOPODA. 18 
Goniatites Henslowi. Plate I. fig. 6. G. sphericus. 
Plate III. fig. 14. 
This genus was formerly included among the Ammonites, but was separated 
by Von Buch. It is unknown in the superior strata. The septa, lobes, and 
sinuses differ from those of Nautilus and Ammonites. See plate I. fig. 2. 
The parts are included within lines—D the dorsal region, L the lateral 
Fegion, and M the marginal or umbilical region; a b c marks the lobes, and 
ee e the sinuses; the siphuncle is distinguished by S, and is situated in the 
centre of the dorsal lobe, immediately beneath the barb of the arrow which 
marks its centre. This belongs to G. striatus. 
The Goniatites Henslowi, plate I. fig. 6, is one of the earliest forms of this 
genus, and which becomes extinct with the Transition series. It is found in 
the Transition Limestone in the Isle of Man. 
Goniatites sphericus, plate I. fig. 13, is a longitudinal view, introduced to 
exhibit the character of the lobes. It shews the position of the siphuncle, 
situate upon the dorsal margin, with its collar protruding outwards, and situate 
between the two simple dorsal lobes ; the lateral lobes are also simple, desti- 
tute of foliations, and are pointed inwards, 
Genus VII. — SCAPHITES, — Parkinson. 
Generic Character.— Shell chambered, involute ; its first 
volutions small, and increasing very gradually ; its last 
elongated and dilated or expanded ; the division of the 
chambers lobed and sinuous. It appears to be almost, if 
not wholly internal, 
Scaphites equalis.- Plate II. fig. 23. 
This genus is allied to Ammonites, but differs considerably in its general 
form, in consequence of the singular extension and inflation of its last cham- 
ber. The species are found, very rarely, in the three contiguous strata, the 
Chalk, Chalkmarl, and Greensand of Wiltshire and Sussex in England, and 
similar beds near Rouen in Normandy. 
Genus VIII. — AMMONOCERAS, — Lamarck. 
Generic Character. — Shell horn-shaped, arcuated, sub- 
semicircular ; the walls articulated with sinuous, laciniate, 
branched sutures; provided with transverse, sinuous, and 
imperforate septa; having lobed, laciniate margins, fur- 
nished with a marginal siphuncle, which does not perforate 
the septa. 
Ammonoceras glossoidea. Plate II. fig. 2. Found only 
in a fossil state, in the East Indies. It is of large dimen- 
sions, measuring upwards of nineteen inches in length. 
Sowerby is of opinion, that this genus should be united to that of Ammo- 
nites, and thinks the specimen from which Lamarck took his generic character 
was only a worn shell of that genus. 
Genus IX.— ORBULITES. — Lamarck. 
Generic Character.— Shell subdiscoidal, spiral, with con- 
tiguous yolutions, the last enveloping the inner ones ; the 
