Annals of the Transvaal Museum 
21 
and flanks round off imperceptibly into each other. The umbilicus is very 
narrow. The flank rounds ofl broadly into the umbilical surface, which is high 
and slightly convex and somewhat sloping towards the centre. The innermost 
portion of the umbilical surface slopes away from the centre and towards the 
plane of symmetry, and therefore the radius of the umbilical suture is longer 
than that of the umbilical surface immediately adjoining the suture. The 
involution is such, that only an extremely narrow strip of the preceding whorl 
remains uncovered. 
The surface of the shell of both specimens is badly preserved ; as far as can 
be ascertained the shell is smooth and covered by fine growth-lines. Old 
mouth-edges have not been observed. 
The lobe-line is built after the type of Desmoceres latidorsatum Mich. sp. 
and D. diphylloides Forbes sp. It is greatly incised. The saddles are not only 
bifid, but each portion is subdivided again and again. The lobes, except the 
Text-fig. II. Desmoceras crassum. Lobe-line of type up to near the umbilical 
suture on a radius of i6 mm. x 3*5. 
external one, are irregularly trifid. The external lobe is just as long as the first 
lateral one. The siphonal saddle is remarkably small. Nine saddles are visible 
up to the smallest diameter of the umbilical surface. These are arranged in a 
straight line and diminish gradually in height towards the umbilicus. 
Measurements : 
Type 
Paratype 
Diameter 
34*6 
mm. (I'oo) 
30-2 
mm. (i-oo) 
Height of last whorl ... 
20-1 
» (0*58) 
17*3 
» (0-57) 
Thickness of last whorl 
i6-3 
.. (0*47) 
13-5 
» (0-45) 
Height of penultimate whorl . . . 
8 
» (0’23) 
Thickness of penultimate whorl 
7 
,, (0-20) 
Diameter of umbilicus... 
2*8 
,, (0'08) 
Desmoceras crassum greatly resembles D. pyrenaicum de Qross. ( 10 , PI. 
XXV, fig. 2, now PI. XXXVII, fig. 9). The relations of height and breadth of 
the last whorl are, however, different. The umbilicus of our fornl is much 
smaller and its lobe-line is far more complicated. 
I am not aware of any other form with which the present species could be 
confounded. Especially in its dimensions it differs from similar forms. 
Only two fragmentary specimens have been found. 
Desmoceras compactum n.sp. PI. IV, figs. 5 — 7, text-fig. 12. 
Shell thin, discoidal, umbilicated. Whorls higher than broad. Greatest 
thickness of the whorl at the junction of external surface and flanks. Sides of 
whorl flattened, converging slightly towards the umbilicus. External surface 
