38 
Annals of the Transvaal Museum 
Measurements : 
Type 
Diameter ... 
65 mm. 
(I'OO) 
29-7 mm. 
(i-oo) 27-3 mm. (i-oo) 
Height of last whorl 
29*8 ,, 
(0-46) 
15-4 
(0-52) 13-8 
» (0-51) 
Thickness of last whorl . . . 
20 ,, 
(0-31) 
10-9 ,, 
(0-36) 9 
( 0 - 33 ) 
Height of penult, whorl ... 
16 
(0-25) 
6-8 „ 
(0-23) 5*9 
,, (0-22) 
Thickness of penult, whorl 
10-8 ,, 
(0-17) 
6 
(0-20) 4-6 
» (0-17) 
Diameter of umbilicus . . . 
15-7 
(0-24) 
5-7 » 
(0-19) 4-8 
„ (o-i8) 
Diameter 
00 
mm. (i-oo) 
26 mm. 
(I-oo) 
Height of last whorl . . . 
12*9 
„ (0-48) 
12 
(0-46) 
Thickness of last whorl 
8-5 
» (0-32) 
10-3 „ 
(0-40) 
Height of penultimate whorl . . . 
5-6 
„ (0-21) 
5-7 » 
(0-22) 
Thickness of penultimate whorl 
4 
„ ( 0 - 15 ) 
5-7 » 
(0-22) 
Diameter of umbilicus... 
5 
» ( 0 - 19 ) 
5*7 .. 
(0-22) 
Six specimens of this variety are present, the largest of which 
has been 
taken as the type. 
The large specimens of var. Grieshachi resemble somewhat Schloenhachia 
Fournien de Gross. ( 10 , PL XXXV, fig. i). They, however, do not possess the 
shoulder tubercles of this species. The small specimens of var. spinifera look 
remarkably like the side view of Munieviceras Lappaventi de Gross, {l.c., fig. 3). 
Our specimens differ especially from Schloenhachia Blanfovdiana Stol. sp. ( 4 , 
p. 46, PI. XXVI) in the absence of the row of tubercles on the middle of the 
flanks, which characterizes this species. 
Two pathological specimens have been found, both apparently belonging 
to the variety Grieshachi. In both the keel is not in the plane of symmetry, 
having moved, more or less, on to one of the flanks. In one specimen this has 
taken place to such an extent, that the ribs of one side pass over the outer 
contour on to the other side. As a result the outer contour is somewhat wavy. 
Genus MORTONICERAS Meek. 
Mortoniceras Soutoni Baily sp. Pis. X, XI, text-figs. 19 — 22. 
1855. Ammonites Soutonii Baily, 3 , p. 455, PI. XI, fig. i. 
1895. Mortoniceras Soutoni Kossmat, 12 , p. 88. 
1904- Mortoniceras? Soutoni Solger, 16 , p. 205. 
1906. Mortoniceras Soutoni 17 , p. 337, PI. XLIII, fig. i. 
There are four fairly complete specimens and a fragment of a larger one 
of this species in the museum collection. Three of these were bought from 
Mr Venter, another was presented by Mr D. Strachan, while the last was 
found by the Museum Expedition. A description in extenso of this species will 
not be out of place. 
Shell discoidal, umbihcated, consisting of numerous whorls, which increase 
moderately in size. Whorls higher than broad. Greatest thickness between 
the umbihcal edge and the middle of the flanks, but nearer to the last. External 
surface convex, flanks also convex, but their inner two-thirds only very slightly 
so. There is no demarcation between the external surface and the flanks, un- 
less the row of elongated tubercles on each side of the keel is taken as such. 
The high umbilical surface is convex, but as a whole practically vertical on 
the plane of symmetry. Between the umbilical surface and the flank the surface 
of the shell is only strongly convex, there being no definite edge. Involution 
about one-fourth. Umbihcus large. 
