26 TYPE AMMONITES— III Nov. 



the application of the family name depends on that and it has not yet 

 been done. 



Perisphinctes, Waagen, 1869 (Form. Am. subradiatus ; Geogn.- 

 Pal. Beitr. II. (2), 248). Proposed for the Planulat.es of the Middle 

 and Upper Jura — all named by that date are thus genosyntypes ; but 

 the author limits choice by the description — that in the young the 

 mouth-border has auricles and the whorls have constrictions. Siemiradzki 

 (Mon. Perisph. ; Pal. XLV, 1899, 78) applies generic name s. str. to 

 certain series more or less connected with Am. martelli. As he has 

 selected no one genotype, and still calls all the species of his six 

 Abtheilungen by the name Perisphinctes, choice is still unfettered and 

 should fall, if possible, on a species fulfilling Waagen's description, 

 named before 1869, and, as the suture-line is very important, on an 

 auriculate showing that feature — a difficult condition, as sometimes 

 suture-line and side-view have, without notice of the fact, been taken 

 from different examples, which may be only homceomorphs. 



The difficulty of such choice is well shown by the following account. 

 It seemed that Ammonites martinsii, d'Orbigny, would be a suitable 

 subject for type : it was doubtless one that Waagen had in mind, for 

 both constrictions and auricles are striking. However, I put certain 

 questions to my friend Professor Welsch. I summarize his interesting 

 information — the result of his study of the types. 



The name is Ammonites martin sii, not A. martinsii, as given in 

 places by d'Orbigny and by so many authors : it was dedicated to 

 M. de Martius, the botanist. The figures given by d'Orbigny are greatly 

 restored, idealized from various examples which are not necessarily the 

 same species; [they are, in fact, synthetographs]. There is no evidence 

 for the auricle of the mouth of fig. 1, PI. cxxv of d'Orbigny, in the 

 example which furnished the main of the figure : the auricle is taken 

 from another specimen, perhaps another species. The mouth of fig. 2 

 is restored as regards the saddles and lobes. The mouth of fig. 3 is 

 imagination. The suture-line is taken from another specimen rather 

 smaller than 210 mm. The proportions are taken from an example 

 of 210 mm. 



With such a mix up as this identification is almost impossible, 

 and it would be unsafe to take Am. martinsii as a genotype. It is 

 advisable, however, to fix on figs. 1, 2, of d'Orbigny 's plate without 

 their months as the holotype of the species. It is presumably about of 

 niortensis-garantiana date. 



Another auriculate species, Am. defrancii, d'Orbigny, PI. cxxix, 7, 

 is not now a Perisphinctes : it belongs to the Morphoceratida;. Another 

 auriculate, Am. bakarice, d'Orbigny, PI. cxlix, 1, has been taken as 

 type of the genus Siemiradzkia, Hyatt ; it therefore falls out. Another 

 candidate might be Am. achiles, d'Orb., PI. ccvi, 1, 2 ; but this is 

 excluded from the species by Dr. Siemiradzki, who gives an opinion 

 on its identity. As this lacks s.l. and may be a synthetograph like 

 Am. martinsii and as it is impossible to go on with the necessary investiga- 

 tions for each likely species, it seems advisable to return to Siemiradzki 's 

 position : this is helped by the fact that a small specimen of, or near to, 

 Siemiradzki's Perisphinctes s. str. has been found at Cowley, near 

 Oxford, S.B. Coll. No. 3264, showing a lateral auricle. Whether, however, 

 this is a brephomorph or a phaulomorph is not yet certain. 



For genolectotype of Perisphinctes is now selected Am. biplex, 

 Sowerby ; it is, which is important, a species figured before Waagen 

 founded the genus. Its suture-line is partly visible : Dr. W. D. Lang 



