562 MOLLUSCA SUB-KINGDOM VI 
Sub-Order G. PHYLLOCAMPYLI. Hyatt. 
An extensive series of genera having saddles with rounded outlines in primitive forms, 
and as a rule with phylloidal bases in sutwres with divided lobes. When the saddles are 
completely divided by marginal lobes, the marginal saddles still retain the same mono- 
phyllic outline. Dorsal lobes and saddles generally numerous, except in primitive forms. 
Antisiphonal lobe entire only in primitive forms, becoming bifid with more or less 
persistently entire sides in some groups even in the Jura and Cretaceous, but in others 
they may become either bifid or trifid, and in highly specialised Triassic forms may acquire 
considerable complexity of outline. The zygous dorsal saddles are commonly monophyllic. 
I. PROLECANITIDA. 
The young in-this growp have an ibergiceran stage (Karpinsky) with very long un- 
divided ventral lobe. Primitive forms are compressed, discoidal, and more specialised 
genera become involute and assume a inodified anarcestean aspect. Saddles are entire in 
the former, but the first laterals become very large and are subdivided by simple marginal 
lobes. Lateral lobes entire in primitive genera, and become 
bifid or trifid in specialised forms, but rarely have more 
numerous digitations. Antisiphonal lobe entire or pointed. 
Siphuncle without calcareous sheath ; funnels monochoanitic 
so far as known. 
Family 1. Prolecanitidae. Shells discoidal or 
involute, compressed, subquadrate, or helmet-shaped in 
section, but never semilunate except during the anarcestean 
stage of the young. Primitive forms have undivided 
ventral lobes, and rounded saddles and lobes of the 
lecanitean type; sometimes also they have large inner 
saddles showing derivation from Magnosellaridae, Wut 
there are not less than two lateral lobes. More specialised 
shells have entire hastate lobes and saddles, and similar 
but divided ventral lobes. Aperture with well-marked 
Fic. 1155. hyponomic sinus. Shells smooth 
Prolecanites lunulicosta, Sandb. Or costated, and often with longi- 
CUE et sea gre Nassau (after 4ydinal ridges. 
Ibergiceras, Karp.; Prolecanites, 
Mojs. (Fig. 1155); Agathiceras, Doryceras, Adrianites, Clino- 
lobus, Gemm. Devonian to Permian. 
Family 2. Noritidae. Waagen. Similar to Prolecani- 
tidae, but the ventral lobe instead of becoming divided in the 
usual way, retains the larval trifid stage throughout life in 
primitive species. In specialised forms the larval siphonal 
saddles enlarge in the neanic stage, 
thus building up a single siphonal 
saddle with a comparatively large 
siphonal lobe. First lateral lobes may 
_ be bifid, trifid, or completely digitated 
Suture-line of Norites . 6 oar Pronorites cyclolobus, Phill. 
Gondola, Mojs. Muschelkalk ; 12 specialised shells, and when the sp. Carboniferous Lime- 
Schreyer-Alp, near Hallstadt, second and other lateral lobes also Stone; Grassington, York- 
Austria. shire (after Phillips). 


Fia. 1157. Fig. 1156. 
become digitated the outlines are 
ceratitic. The saddles, however, retain more or less of their primitive outlines, and 
their bases are entire. Sutures without true adventitious inflections. Apertures 
have crests at the ventro-lateral angles; straight or with faint sutures at the venter, 
hut replaced hy slight crests in some Triassic genera. 
