Annals of the Transvaal Museum 
9 
very fine and narrow, and generally divided into two or three at about the 
middle of the whorls. Prof. Dr G. Giirich, the director of the Mineralogisch- 
Geologisches Institut of Hamburg, kindly sent me casts of Griesbach’s speci- 
men, and these place it practically beyond doubt, that this specimen belongs 
to the present species. 
Only one specimen of this species has been found. 
Gaudryceras Sigcau n.sp. PI. II, figs. 13 — 16, text-fig. 5. 
Shell discoidal, umbilicated, consisting of many whorls, which at first in- 
crease slowly and afterwards more rapidly in size (both specimens have at 
least five whorls at a diameter of ii mm.). Greatest thickness of last whorl 
internal to the middle of the flanks; of the preceding whorl on the middle of 
the flanks. Sides of whorl and external surface convex. There is no demarca- 
tion between the external surface and the flanks. The convexity is slightly 
increased between the flanks and the umbilical surface. Umbilical surface 
sloping inwards from the flanks. Involution about one-half. 
The ornamentation of the shell is extremely fine and practically invisible 
to the naked eye. It consists of numerous, very fine, narrow, low, line-like 
ribs. I do not call these ribs hair-like or thread-like, because they differ from 
those of Gaudryceras tenuilineatum for example. The interspaces between the 
ribs are flat and of irregular breadth but always much broader than these. 
The ribs are slightly concave forwards on the umbilical surface and on the 
umbilical edge. They run slightly forwards on the flanks, are slightly convex 
forwards on the middle and very slightly concave 
forwards on the external portion of the flanks, while 
they are again very slightly convex forwards on 
the external surface. Old mouth-edges have not been 
noticed. 
The lobe-line is a typical Gaudryceras one. The ex- 
ternal lobe is narrow and has the same length as the 
first lateral lobe. The external saddle and the first 
lateral saddle are both symmetrically divided by a 
secondary lobe. The second lateral saddle is unsym- 
metrical. Both lateral lobes and the first auxiliary lobe 
are bifid. The outer portion of the first lateral lobe is 
bigger than the inner portion. At a diameter of 
4-5 mm. there are three auxiliary saddles. From the first lateral saddle the 
lobe-line runs backwards and inwards towards the umbilical suture. 
Text-fig. 5. Gaudry* 
ceras Sigcau. Lobe- 
line of paratype up 
to the umbilical su- 
ture on a radius of 
4*5 mm. xy. 
Measurements : 
Type 
Paratype 
Diameter 
11*6 mm. (i*oo) 
iiM mm. 
(i-oo) 
Height of last whorl ... 
4-6 „ (0-40) 
4-7 » 
(0-42) 
Thickness of last whorl 
4*5 ( 0 - 39 ) 
4 
(0-36) 
Height of penultimate whorl 
2 „ (0-17) 
2 
(o-i8) 
Thickness of penultimate whorl 
3 » (0-26) 
2-9 „ 
(0-26) 
Diameter of umbilicus 
3-9 ( 0 - 34 ) 
4 
(0-36) 
This pretty little ammonite is 
easily distinguished from many of the Indian 
Gaudryceras species. The height of the whorls surpasses the breadth quicker 
in our form than in most of the Indian ones. The relations of our form differ 
markedly from some other Indian species. Gaudryceras involvulum Stol. sp. 
and G. revelatum Stol. sp., show differences in the lobe-line. G. politissimum 
Kossmat differs in shape, number of whorls and in the lobe-line. G. odiense 
Kossmat has a different shape. G. varuna Forbes sp. differs in shape and 
