282 THE LIAS AMMONITES. 



stair-like character to the open umbiUcus (figs. 4 and 5). The aperture is quadrate (fig. 2), 

 the width slightly exceeding the height. The septa are symmetrical, foliated on each side, 

 and divided into four lobes with narrow branches ; the siphonal lobe (fig. 3), long and narrow, 

 projects beyond the others ; the outer side has three short simple, two long branched, 

 and one terminal branched digitation ; on the inner side of each bilateral segment of the 

 lobe there are five or six simple digits. The principal lateral lobe is small ; it has five or 

 six long tooth-like lateral digitations on its outer, three or four on its inner side, and 

 bifurcates into two terminal branches ; the inferior lateral lobe is long and slender, with 

 several narrow digitations on the sides, and a bifurcate termination ; the auxiliary lobe is 

 small ; the siphonal saddle is large, but not sufficiently exposed for accurate description ; 

 the lateral saddle is very large, occupying two thirds of the sides of the whorl ; it has two 

 large terminal folioles, and two lateral folioles, with four or five lobules in each. 



Affinities and Differences. — In the quadrate outline of its whorls and its straight 

 simple ribs its resembles A. Valdani, d'Orb. ; and the terminal tubercle on its ribs likens 

 it in form to A. perarmatus, Sow. ; whilst the form of the lobes and saddles, and the 

 median ridge on the back distinguish it from both. It is very distinct from the other 

 species of keelless Arietites, and has no affinities with the keeled species of that group, the 

 absence of sulci on the siphonal area affording a reliable diagnostic character. 



Locality and Stratigraphical Position. — The large specimen was collected in the zone 

 of Arietites obtusiis, near Bredon, during the construction of the Bristol and Birmingham 

 Railway. The smaller specimens were obtained from the same zone at Darlingscott, near 

 Shipton-on-Stour, and given me by my late friend, Mr. John Kirshaw, of Warwick. I 

 have found one or two small specimens in the Lower Lias of the Vale of Gloucester, and 

 my friend, R. Etheridge, Esq., E.R.S., collected a specimen from the railway-cutting at 

 Horfield, near Bristol. There are several fine large examples of this Ammonite in the 

 stock cases of the British Museum ; unfortunately their locality is unknown. Arietites 

 Saugeanus has been obtained from Lias nodules found in Drift on the Holderness Coast, 

 and from the Lower Lias, Robin Hood's Bay, Yorkshire Coast. It is the true Ammo- 

 nites resupinatus and Amm. transformatus of Simpson. It is curious that this remarkable 

 Ammonite should have been found in England, France, and Germany about the same 

 time. 



Arietites Sauzeanus is a very rare Ammonite in Prance, M. d'Orbigny states that 

 he had seen only two specimens of this singular species, which were collected from the 

 Gryphcea arcuata beds of the Lower Lias by M. Boucault, at Champlong, near Semur 

 (Cote d'Or), where it is very rare. 



