ORDER II AMMONOIDEA. 551 
Sub-Order D. EURYCAMPYLI. Hyatt. 
Conchs varying in primitive genera from forms like Anarcestes to highly coronate 
with entire lobes and saddles. The ventral and lateral lobes become divided in specialised 
Palaeozoic genera, and the more highly specialised Permian and Triassic forms have the 
lobes and saddles completely divided. The large inner saddles characteristic of the ephebic 
stage of Magnosellaridae are retained throughout life in many Palaeozoic forms, and 
occur more or less in the young of Triassic genera. Among the latter the coronate form 
of Gastrioceras is also common. 
I. MAGNOSELLARIDA. 
Prevailing form of conch Anarcestes-like, but sometimes discoidal, and more or less 
quadrangular or trapezoidal in section. Sutures entire, with large inner lateral saddles 
resembling those of Glyphioceras in most Palaeozoic forms, but the lobes become more 
digitated in some Carboniferous and Permian genera, and both lobes and saddles are 
completely divided in highly specialised Triassic genera. Ventral lobe undivided in 
primitive forms, but split by a siphonal saddle which is in turn subdivided by minute 
funnel lobes in the more specialised species. Siphuncle without calcareous sheath ; funnels 
monochoanitic in primitive forms, and diplochoanitic or sometimes even chloiochoanitic in 
specialised Permian forms. 
Primitive genera have deep undivided antisiphonal lobes and only one pair of 
large broad dorsal saddles; the first pair of lobes, when present, are confluent with 
the second lateral lobes at the lines of involution. More specialised shells may retain 
a pointed undivided antisiphonal, but the dorsals may have one pair of entire narrow 
saddles, one pair of entire pointed lobes, and usually a second pair of saddles. These 
last are broad, similar to the lateral pair, or confluent with the third laterals when 
there is a third external pair. 
Family 1. Magnosellaridae. Beyrich. Ammoniticones varying from discoidal 
and Anarcestes-like to highly involute, 
compressed shells with narrow venters. 
Septa concave along the mesal plane as 
in Nautiloids, becoming convex only 
internally and laterally, following the 
broad internal saddles in the zone of 
involution. Lobes and saddles entire. 
Primitive forms may have only two 
broad saddles on either side, but more. 

specialised shells may have two pairs of Fic. 1126. Fic. 1127. 
principal saddles formed by division of — Zornoceras retrorsus, v. Buch. : He simpler, y. 
Ser p sei : Jpper Devonian ; Biidesheim uch. pper Devonian ; 
the primitive first laterals. There is a pb" yyvou™ se? Badeshebne WUE, 
corresponding development of narrow 
saddles and lobes on the dorsum, but primitive forms have only two broad saddles 
here as in Anarcestes. Anti- 
: ! : ; siphonal lobe narrow, entire, 
Se ie tae: ate VN AG 2 pointed. Aperture with hypo- 
nomic sinus. Shells smooth. 
cy £ Ce 9 - . 
ee Bige iz2. Parodoceras (Cheiloceras, 
Suture-line of Sporadoceras Suture-line of Maeneceras tere- yr. nI4\ ~ Toompeore (Bios 2 
Miinsteri, v. Buch. sp. brutus, Sandb. sp. Frech) ; Tornoceras (Figs. 1126, 
1127), Sporadoceras (Fig. 1128), 
Maeneceras, Hyatt (Fig. 1129); Paratornoceras, gen. nov. Type P. (Gon.) lentiforme, 
Kayser sp. Gonioloboceras, gen. nov. Type G. (Gon.) goniolobus, Meek_sp. Pseudo- 
clymenia, Frech. Devonian and Carboniferous. 
Family 2. Pericyclidae. Involute shells resembling Glyphioceratidae, but haying 
