22 TYPE AMMONITES—I 1 1 1920 



Family SPHMROCERATIDM, nov. 



Suture-line with OV on, later inside, of a broad-stemmed, spread- 

 ing L 2 , which is more or less unequal-sided, the suspensive lobe feebly 

 developed, and no highly-elaborated auxiliary lobe. 



Genera Sphceroceras, Bayle, 1878, Emileia, Buckman 1898, Otoites, 

 Chondroceras, Mascke 1907, Docidoceras, Labyrinthoceras, Trilobiticeras, 

 Morrisiceras, Buckman 1919, 1920, and Macrocephalites, to be removed 

 from Pachyceratidse. 



It seems inadvisable to employ the family name Otoitidae, Mascke, 

 as the present grouping is so very different. Several of these genera are 

 distinctly sphasroconic, Emileia passes through it and becomes platy- 

 conic ; but Docidoceras is an exception : it develops serpenticones without 

 passing through a sphairocone stage. 



It will be noticed that genera with lateral auricles come into 

 Stepheoceratidae and Sphaeroceratidas. Such forms are regarded as 

 phaulomorphs. Suture-line is considered to be a better test of affinity 

 than mouth-border. 



Family MORPHOCERATIDAt, Hyatt, 1900. 



This requires much emendation. All the genera given by Hyatt 

 (Eastman-Zittel, Pal. 1900, p. 583) must be excluded, except Morphoceras. 

 There may be added Oecoptychius, Neumayr, and new genera, (Ecoptych- 

 oceras and Ebrayiceras (see below). 



The family is in origin presumably akin to the Sphaeroceratidse, 

 and it develops sphasrocones out of which come, normally, serpenticones — 

 the transition from sphaerocone to serpenticone is so rapid in some cases 

 as to give the curious ' dimorphous ' feature — and, abnormally, gonio- 

 cones — the same transition in an exaggerated form. 



The difference from Sphasroceratidae is the suture-line — comparatively 

 simple, with L 2 compact, not spreading ; retraction feeble, sometimes 

 lost — phylogerontic development. 



Morphoceras, H. Douville, 1881 (" Am. pseudo-anceps " ; Bull. Soc. 

 Geol. Fr. (3) VIII, 242). " Type : A. polymorphus .... Cloisons 

 presentant une serie de lobes regulierement decroissants." 



There are 4 specimens figured in d'Orbigny (PI. cxxiv) belonging 

 to two, if not more, species. These are syntypes. The s.l. (fig. 7) 

 shows the characters cited above, and from d'Orbigny's text (p. 381) is 

 presumably taken from fig. 4. Therefore this specimen is chosen as 

 genolectotype. 



Add — ribs, furcation twice — inside L 2 and sometimes again outside 

 it. Periphery with smooth median line, into which fade ribs that 

 alternate ; constrictions well-marked cutting across 4 or 5 ribs. Mouth 

 not known to be auriculate. S.l. — lobes rather broad-stemmed, E.S. 

 narrow, E.L. and L l approximate, L 2 nearly as long as L l , all lobes 

 touching guide-line. 



Ebrayiceras, g.n. Genoholotype E. ocellatum, n. PI. CLXXIII. 

 Furcation single — on or inside L 2 ; primaries short, swollen ; periphery 

 sulcate, ribs thereon not quite opposite, ending as feeble nodi abruptly 

 at interruption ; constrictions feeble, nearly parallel with ribs. Mouth 



