180 INFERIOR OOLITE AMMONITES. 



he observed (p. 60) concerning the suture-line, " Bei dem kleinen Am. suhserrodens 

 sind der 1. und 2. Seitenlobus relativ schnialer und tiefer und enden dreispitzig ; 

 bei dem ffrosseren Am. Fridericii ist Alles einfacher." 



The species itself Branco describes as follows : 



" Im ausgewachsenen Zustande besitzt diese, der vorigen verwandte Art 5 

 Umgange, welche massig rasch in die Hohe wachsen. Vom Nabel aus steigen die 

 wenig gewolbten Seiten anfangs mit geringer Convergenz empor, um sich spater 

 rasch in der scharfen Externseite zu vereinigen, die keinen abgesetzten Kiel 

 tragt. Die Schaale zeigt feine Anwachsstreifen, von welchen auf dem Steinkerne 

 jedoch keine Spur bemerkbar ist. Auf dem letzten Umgange stellt sich eine (auf 

 der Abbildung ungeniigend wiedergegebene) Nathflache ein, welche ziemlich steil 

 gegen den Nabel hinabfallt." 



The above description agrees perfectly with the specimens which I have 

 figured except in two ways. " The ventral area bearing no keel set upon it " is 

 not according to my description ; but it really depends on how we consider the 

 matter. The carina is in reality no more than a compression of the two sides of 

 the ventral area, and that it forms a very prominent object is shown by Branco's 

 fig. 2 a, in which what I should call the carina — but he regards as the sharpened 

 outside — appears more prominent than in my specimens. 



The other matter is that " there is no trace of the fine growth-lines to be 

 detected upon the core." Now, most of my specimens show well-marked 

 growth-lines upon the core (Plate XXXI, figs. 5, 10, 13) ; but I must also remark 

 that, in some more poorly-preserved examples, the growth-lines are certainly to 

 be detected only with great difficulty, and the specimens really appear quite smooth. 

 Practically speaking the suture-line of this species differs from that of Grammoceras 

 only in possessing an inferior lateral lobe rather longer, and the incipient auxiliary 

 lobes more numerous ; but these facts are exactly what we might expect on 

 account of the more extended side. 



It is this stretching in order to accommodate itself to the increased side that 

 causes the suture-line to appear somewhat more like that of Pelecoceras {Am.- 

 sierrodens-grovo^) ; yet Branco's own drawings show the difference in this respect. 

 In Pelecoceras (i. e. A'^n. Fridericii) the suture-line is little more than a jagged 

 waved line, slightly lower where the lobes are. In this species the superior and 

 inferior lateral lobes are at any rate well-marked and distinctly protruded. 



This species occurs in the same bed as Gramm. mactra ; and I should be 

 entirely disposed to regard it as a further development of the form a of that 

 species were it not that some of the young specimens of this one seem to be too 

 coarsely ribbed. However, if not a direct descendant of Gramm. mactra, it has 

 evidently sprung from the same stock, and has made more use of its time to 

 attain a smaller umbilicus. In having a smaller umbilicus, broader whorls, and 



