108 INFERIOR OOLITE AMMONITES. 



ship and their position in the genetic series, and would convey a definite idea with 

 regard to their general appearance, not to be obtained otherwise except by a 

 lengthy description. 



This is the only specimen of this species which I have seen. It was in the 

 collection of Mr. T. 0. Maggs, F.Gr.S., and was obtained from Clatcombe, near 

 Sherborne, Dorset. Its geological position is rather uncertain, but I judge it to 

 be either the Murchisonce-zone or the CWcarom-beds. 



Hildoceratim; (continued). 

 Genus — Lillia, 1 Bayle, emend. Haug. 



1878. Lillia, Bayle. Explication carte geol. France ; explanation of pi. lxxxuV 



fig. 1. 

 1885. Lillia, ILaug. Beitriige Monog. Harpoceras ; Neues Jahrbuch fur Mineral- 

 ogie, &c, Beil.-Bd. iii, p. 713. 



{Type — Lillia comensis, von Buch, sp.) 



Definition. — Discoidal, carinate ; whorls subquadrangular, ornamented with 

 small knobs or protuberances placed at more or less irregular intervals on the 

 inner margin, from which, or from between which, prominences proceed ribs, 

 rather straight on the lateral area, but with a forward sweep on the ventral area. 

 This area is broad and somewhat flattened, carrying two furrows on each side of a 

 small but well-marked solid carina. The suture-line has a rather long and narrow 

 siphonal lobe, a rather wide siphonal saddle, a large superior lateral lobe, a small 

 inferior lateral, and one or two small auxiliaries. 



Remarks . — The straight ribs on the lateral area and the knobs or pro- 

 tuberances on the inner edge separate this genus from any of the preceding, as 

 also do its suture-line and the possession of furrows on each side of the carina. 

 The nearest approach to the ornamentation of this genus is seen in youngp 

 specimens of Ludwigia Murchisonce (Plate II, fig. 3), and especially in young 

 specimens of L. obtusa — with their knobs on the inner area, whorls inclined to be 

 quadrangular, and traces of furrows on the ventral area. In fact, it appears to me 

 to be extremely probable (especially since I have had the opportunity to examine 



to drop the one for the other. I consider that both terms mark their special stages in Ammonital 

 development — the special features in each stage being for a time very persistent in the species referred 

 thereto. 



1 Hyatt's Genus Phyrnatoceras was probably proposed for the same series of species ; but he gave 

 neither a figure nor a reference to any known species, so that we cannot make use of his name. 



