HAUGIA JUGOSA. 151 



former, and the usual rules of development are carried out in supposing this 

 relationship. 



The identification of Sowerby's Am. jugosus would have been a practically 

 impossible task without an examination of the type specimen ; and this arises 

 from the incorrectness of his delineation — an incorrectness which is not observ- 

 able in the Ammonites of the " Mineral Conchology " taken as a whole. A 

 comparison of his plate scii, fig. 1, with the figure which Mr. Gawan has drawn 

 in this Monograph (Plate XXIII, fig. 11) will, on account of the broken portion, 

 &c., show at once that the same specimen has been the subject in both instances, 

 But Sowerby's^ figure shows whorls much too narrow, and without the faint 

 tubercles ; also it exhibits an umbilicus considerably too large, and with too many 

 whorls over much exposed. 



It is unfortunate that Dumortier's Am. Ogerieni, which is both well delineated 

 and described, should have to yield to Sowerby's Ain. jugosus. Still, before 

 Dumortier had given this name Waagen had announced the relationship of 

 Sowerby's species when he wrote concerning the shell which Oppel had called Am. 

 jugosus, " Nachdem ich nach Besichtigung des Sowerby'schen Originalexemplars 

 mich veranlasst sehe, der Ansicht der Englischen Paliiontologen beizutreten, und 

 A. jugosus, Sow. 92 fiir eine Species des Oberen Lias, dem A. variabilis, Orb. 

 nahestehend, zu erklaren, ist es nothig den Ammoniten der Sowerbyi-Schicht, den 

 Oppel hier in Auge hatte, neu zu benennen."^ 



H. jugosa is really the species most characteristic of the harder beds of the 

 Cotteswold Sands, and not H. variahilis as my term Variahilis-snhzone might imply 

 (p. 148). Dumortier also says of this species {Ogerieni), {op. cit., p. 79), " Cette 

 jolie espece est plus repandue que VA. variabilis, avec laquelle elle paroit avoir ete 

 toujours confondue." 



Since the Cotteswold Sands are not utilised for any economic purpose, 

 exposures of these strata are limited, and are only to be found where old cart-tracks 

 have worn a deep road through the soft beds on the hillside. The consequence is 

 that specimens of this species are hard to obtain, and, even then, are not unfre- 

 quently crushed and worthless. Judging however from the specimens obtained 

 from such limited exposures the species must have been fairly abundant. It is 

 found at Coaley Wood (Bed 16— p, 45) and North Nibley (Beds 28 and 30— p. 46). 



Plate XXIII, figs. 11, 12, represent the type specimen of this species — being 

 the original Am. jugosus figured by Sowerby ; but, as a comparison with his work 

 will show, his figure was most inaccurate and misleading : fig. 13 is the suture-line 

 of this specimen as nearly as the artist was able to trace it. Figs. 14, 15 exhibit 



' On account of the state of preservation of the specimen these tubercles might easily have escaped 

 the observation of anyone not acquainted with Ammonites of this species. 



* " Zone Amm. Soiverbi/i," ' Geogn. Pal. Beitrage,' p. 595 (Amm. Gingensis), 1867. 



