part 1] JURASSIC CHRONOLOGY : LIAS. 91 



Pompeckj, and 'Ammonites angulatus, young shell,' Wright, 1 

 a Schlotheimian phaulomorph ; in the Lymian, Ammonites per- 

 sonatus, an Agassiceratan phaulomorph, with Agassiceras spinaries 

 Quenstedt, and other like forms as nomomorphs. Agassiceras 

 halecis J. Buckman is, presumably, a brephomorph ; and some 

 other species of Agassiceras are anamorphs. In the Deiran. 

 Oheltonia is a phaulomorph; its nomomorph is Oxynoticeras 

 oxynotum, which, however, is usually found much broken down — ■ 

 only as air-chambers — truncated nomomorphs, or so much reduced 

 as to be quite small — colomorphs. Occasionally, specimens about 

 6 times the usual size are reported, which is in accordance with 

 expectation ; for it makes Oxynoticeras agree better with its 

 allies, Qleviceras ~ and Radstockicerasfi 



In the Domerian, Amaltheus Icevis (Quenstedt) is obviously an 

 Amaltheid phaulomorph. 



The foregoing statements about phaulomorphs refer, not only to 

 British, but to the Continental Lias generally. However, in the 

 Middle Lias of Italy are two peculiar genera which certainly 

 have the appearance of being phaulomorphs — Diaplwrites and 

 Pimelites Fucini," 1 {Prcesphceroceras Levi). 5 Their family posi- 

 tion is doubtful — Phylloceratida j according to Fucini, Dactyloidse 

 according to Hyatt. The strange suture-line with a much extended 

 superior lateral lobe seems to have some resemblance to that of 

 Gagaticeras, 6 so it seems to me possible that they are phaulo- 

 morphs of the Liparoceratidse. 



In the Inferior Oolite phaulomorphs abound — incipient scaphiti- 

 cones, with considerable development of lateral auricles — Otoites, 

 Norman nites, and Cadomoceras may be cited as examples : here 

 publication failure comes in — there are man}' new and strange 

 forms yet to be figured. 7 



The largest megalomorph ammonites occur in the Jurassic at 

 two periods, near the beginning and towards the close — Lower 

 Lias and Portlandian. In between, the times of Inferior Oolite 

 (Bajocian-Yesulian) and Corallian (Argovian) show some good 

 megalomorphs ; but few attain such gigantic size as do the species 

 of the earlier and later dates. 



A considerable number of megalomorph ammonites must be 

 extracted from the quarries and other excavations in this country 

 every year, and be almost wholly lost to science. Should they 

 escape the sledge-hammer of the quarrymen, they may find a 

 temporary home on some rockery, to be destroyed by frost in a few 

 years or broken tip for road-metal on a change of occupiers. 

 Barely, they may be rescued from the quarryman or the rockery by 

 the geologist ; but even then their safety may not be assured — not 



1 XXIII, pi. i, fig. 5 only. 



- II, 8, p. 289 ; p. 291, 450 mm. 3 Ibid. p. 287 ; 380 mm. 



4 VII, pp. 234, 236 & pi. xxv. 5 IX, p. 275. 



(i II, 4, pi. lxxviii, fig. 3. 



7 Trilobit icevas has been figured since this was written (II, 9, pi. cxl). 

 There are many species of this genus all new. 



