1926 SYSTEMATIC ii 



Liassic species on the surer footing of pictorial representation ; but 

 there is still much to be done. Rejections of names because their types 

 lack illustration is easy, but it is not correct work. Mr. Crickmay took 

 a satisfactory course, that of hunting out Hyatt's types and illustrating 

 them. It is to be hoped that he will continue that good work. 



However, the possession of a figure of a species does not necessarily 

 end all troubles. A bad figure may cause more worry than no figure 

 at all. Figures may be synthetographs, drawn purposely from more 

 than one specimen, or depicted by oversight of the artist from more 

 than one example. This is the case, presumably, with Young & Bird's 

 figures of Ammonites redcarensis, which now has to be considered. 



A. redcarensis: Young & Bird's original description (1822, p. 248) 

 is as follows : — " No. 13, PI. XIV, has also [like a maculatus] sharp ribs, 

 and has a sharp keel running along the back. It occurs in the lowest 

 shale at Robin Hood's Bay, and other places. A large shell, generally 

 found imjjerfect, but apparently of the same species, occurs in the Redcar 

 rocks. The a. Bucklandi of Sowerby, Tab. 130, seems to be a cast of 

 this species. We would prefer naming it A. Redcarensis." 



The figure then given by Young & Bird (photographic copy repro- 

 duced T.A. DCVIII, i) shows in its south-west corner a crinkly line 

 on the jjeriphery. Such crinkly line would not represent the carina of 

 a species like Am. bucklandi or obiustis ; rather, it seems to have been 

 drawn from the crinkly edge shown by ribs on the further side of a 

 ventrally-furrowed specimen — the space in the south and south-west of 

 the figure, between the crinkly line and the line bordering the periphery, 

 representing the ventral furrow. 



In the second edition (1828, p. 258) the description is very consider- 

 ably altered : — " No. 10, PI. XIV, from the same beds [as A. Bucklandi 

 in the lowest shale at Redcar, and in Robin Hood's Bay] is obviously 

 a different species [from A. Bucklandi], which we have named A. Redcar- 

 ensis. It is a flatter shell, with the aperture more oblong ; and an 

 imperfect keel, where the ribs, which are bent forward, regularly meet 

 in pairs, at a sharp angle, in the form of arrow-heads. It nearly 

 corresponds with Sowerby's A. Turneri, Tab. 452." 



The figure which is given in this edition differs considerably from 

 that of the first. The periphery has been altered from a crinkly line 

 to a uniform curve, and the whole appearance is that of a carinate- 

 bisulcate like Am. obtusus. 



Therefore in the first edition the description is that of a carinate- 

 bisulcate ; but the figure is, in part, that of a ventrally sulcate ; in the 

 second edition the description, all except the last sentence, is that of a 

 ventrally sulcate without any doubt, but the figure is that of a carinate- 

 bisulcate. It is a remarkable muddle. 



What seems to have hapf)ened is this. Young gave the name 

 redcarensis to a ventrally-sulcate specimen like that sent from Whitby 

 Museum (No. 314) as the original of the species. Bird drew the outline 

 of such a shell, but he filled in other details, partly, at any rate, from 

 a carinate-bisulcate, in error. Then Young, not noticing the substitution, 

 drew up his description from the shell which Bird placed before him. 



In the second edition author and artist, or the two authors, seem 

 to have been again at variance. Young gave a description which would 

 fit a ventrally sulcate, Bird amended his figure so as to depict a carinate- 

 bisulcate. 



