104 danford : notes on the speeton ammonites. 
Zone D (" Bel. lateralis Beds 
In no part of this zone below the Astarte bed D4 have I 
found Ammonites, although they occur there, for Mr. Lamplugh 
says, " De tres petits Ammonites ne sont pas rares dans la 
partie inferieure de la zone (D4, D5, D6, D7), mais elles sont 
difficiles a determiner." These Prof. Pavlow considers resemble 
the iimer whorls of Ammonites of the Olc. suhditus and okensis 
types, while one form from D4 he definitely determines as Olc. 
(Craspedites) fragilis Traut. 
Small Ammonites, often very well preserved, are certainly 
common in D4, and most of them agree with the figures and 
description of Olc. {Grasp.) fragilis in the "Argiles de Speeton,"* 
while others, Mr. Lamplugh thinks " are identical with 0. pli- 
comphalus of the Spilsby sandstone." In this bed may also 
be seen the remains of much larger forms, but not in a state 
admitting of their identification. 
The next bed, D3, contains large and small Ammonites 
of various types. The former are generally mere crumbled 
masses, but some have been partially preserved by incrustations 
of pyrites, and their innermost whorls are occasionally intact. 
They appear to belong to the very globose forms of the Poly- 
ptychites, such as gravesiformis, Keyserlingi, &c., or to the less 
inflated, as Beani, ramulicosta, and perhaps to Lamplughi, a 
species here discovered by Mr. Lamplugh. 
Though distributed through the whole bed, these Ammon- 
ites appear to be commonest above, and a little below the two 
indurated ferruginous bands that traverse it. My best specimens 
came from the top, and belong to Beani and rar)iidicosta. The 
deeper whorled species seem to lie generally, but not always, 
lower. 
Among the smaller forms Olc. (C.) fragilis certainly occurs, 
and there is one in which that variation in the arrangement 
of the ribs where the anterior branch of the umbiHcal rib, after 
passing over the back, joins the succeeding instead of the opposite 
♦"Argiles de Speeton," p. 15. 
