45b YORKSHIRE TYPE AMMONITES Feb. 



45. AMMONITES MACULATUS, Young & Bird 

 (Plate XLV) 



Original Description 

 [Young & Bird, 1822, pp. 248, 327.] 



" No, 12, PI. XIV, is a much smaller shell (than a. acuHcostahis]. 

 from the blue limestone, or rather from alluvial nodules of blueish lime- 

 stone, having also very sharp ribs, but continued round the back ; and 

 having the aperture round. The original shell is brown with some 

 white spots, as in a. Hildensis ; so that we may name this s])ecies a. 

 maculatiis. A similar species, or a variety of the same species, also from 

 the alluvium, has on the sides two small knobs upon each rib ; the one 

 towards the back, and the other, which is the smallest, towards the 

 inside." 



" [P. 327] Plate XIV. Fig. 12. Ammonites maculatiis. Alluvium." 



Additional Details 



Young & Bird, 1828, p. 259. " In the same beds fas A. Hawsker- 

 ensis] we find that beautiful ammonite, No. q, PI. xiv ; which we have 

 named A. maciilatus, as it is usually found of a brown colour, spotted 

 with white or yellow ; though sometimes it is found entirely brown, 

 or dark olive. It is akin to A. gagateus. No. 7, PI. xii : l)eing marked 

 with prominent smooth ribs, which )mss round the back, where they 

 are generally somewhat flattened, and make a sliglit turn ui)vvards. 

 The aperture is circular ; in which respect, and in the more rapid diminu- 

 tion of the whirls, it differs frorn A. gagateus." 



Remarks 



Stages, conch, serpenticone ; jieriphery, i ; ornament. 4, massive. 



(ienus, Androgynoccras, Hyatt ((ien. 777') ; family Lii)aroceralida'. 

 This species presents the Capricorn stage. The s])ecimens with small 

 knobs, mentioned by Young & Bird (1822, 248), and those with inflated 

 whorls, noticed by Simpson (1855, 48), are forms in transition towards 

 Am. heterogenes (No. 46). 



Simpson, 1884, p. xix, enters the species in Lower Lias c. He ]ilaces 

 what he calls .1. capricnrnus 4 beds above, over 20 feet liigher. 



Result 



Androgynoceras maculatum. Young & Bird sp. 1822. |Char- 

 mouthian, striatum zone, near Whitby], alluvium. 



