94 



MANUAL OF THE MOLLUSCA. 



SyH. f orbulites Lam. planulites, Montf. 



Shell, discoidal ; inner whirls more or less concealed ; septa undulated ; 

 sutures lobed and foliated ; siphuncle dorsal. 



Distr., 530 sp. Trias chalk. Coast of Chili (D'Orb.) Santa Fe de 

 Bogota (Hopkins), New Jersey, Europe, and S. India. 



Capt. Alexander Gerard discovered ammonites similar to our L. oolitic- 

 species, in the high passes of the Himalaya, 16,200 feet above the sea. 

 Section A. Bac/c, with an entire Jceel. 



1. Arietes, L. oolites, A. bifrons (pi. III., fig. 6), bisulcatus (pi. 



Ill, fig. 7). 



2. Falciferi, L. oolites, A. serpentinus, radians, hecticus. 



3. Cristati, cretaceous, A. cristatus, rostratus (fig. 55), varians. 



B. Back crenated. 



4. Amalthel, ool. A. amaltheus, cordatus, excavatus. 



A. rhothornagensis (pi. Ill, fig. 4). 



A. discus, clypeiformis. 

 Back channelled. 



A. dentatus, lautus. 

 A. Parkinsoni, anguliferus. 

 Back squared. 



A. armatus, athletus, perarmatus. 



A. capricornus, planicostatus. 



A. Duncaiii, Jason (pi. III., fig. 5). 



Fig. 56. Ammonites coronatus.* 

 F. Back round., convex. 



11. Heterophylli, L. ool. A. heterophyUus (fig. 34). 



12. Ligaii, cret. A. planulatus (pi. Ill, fig. 3). 



13. Annulati, ool. A. annulatus, biplex, giganteus. 



14. Coronati, ool. A. coronatus (fig. 56), sublsevis. 



15. Fimbriati, ool. A. fimbriatus, lineatus, hircinus. 



* Fig. 56. Profile of ammonites coronatus, Brug. (reduced ^ from D'Orbigny) 

 Kelloway rock, France, d 1. dorsal lobe ; ss, dorsal saddles ; V V . lateral lobes ; s's'. 

 lateral saddles; accessory and ventral lobes. The number of accessory lobes increases 

 with age. 



