490 
BeTjEHNites Canhami, Tate. 
e3 
PI. 35, figs. 3-5, 7-9, 12-14 ; ? PI. p, figs. 6 and 7. 
Belcmnitella diptycha, McCoy (ms.), Ann. and Mag. Nat. Hist., 1867, xix., p. 356 ; Ibid,, 1807, xx., p. 196. 
„ ,, „ ,, Tratis. E,. Soc. Viet., 1868, vili., Pt. i, p. 42. 
Bclermvites Canhamij Tate, Proc. R. Soc. S. Auatr. for 1879-80 [1880], p. 104, t. 4, f. 2a-2c. 
Sp. Char. Guard hastate terminating in an acute sub-mucronate, central point, 
contracted in the medio-alvcolar region, compressed vcntro-dorsally, the ratio of the two 
diameters measured at a little further back than at the alveolar apex is as two to three. 
Each dorso-latcral face presents, through the whole length of the alveolar region, a deep 
and sharply cut furrow ; in the region of the alveolar apex it makes an abrupt turn on to the 
medial line of the side of the guard, then splits into two shallow grooves, sejmrated by a 
uniform distance about equal to their own width, which are continued to the apex. 
Phragmacone sub-oblong in its transverse section ; the dorso-ventral diameter is to the 
other in the proportion of eleven to ihirleen ; siphunele sub-internal, and the axis of 
the phragmocone is nearly straight. Length of the guard four inches ; greatest diameter 
is nine-tenths, and the corresponding shortest diameter is six-tenths of an inch ; axis of 
guard two and a-half inches. (Tate.') 
Obs. This sijccies differs from B. australis, PhilL, “ in being more distinctly 
hastate, much more compressed, and in the lateral grooves being continued into a double 
sulcus.” I believe Professor Tate is right in separating from the original figures of 
B. australis, PhilL, two and placing them with the present species. The community of 
form mentioned by Tate is traceable through several specimens examined by me, notwith- 
standing the fact that the lateral grooves are not always well preserved. Thus, in 
PI. 35, figs. 7 and 8, they are faintly visible, through the surface being much worn, but in 
fig. 9 of the same plate they are not to be seen at all 
The specimens before me have yielded the following characters : — The guard is 
sometimes subspathuhite or fusiform, but not greatly flattened, almost circular near the 
distal termination of the alveolar region; thence gradually swelling out, with an elliptical 
section, and slowly acuminating to the posterior end, w'hich is pointed, or mucronate, 
but without an extended mucro. The dorso-lateral grooves at their proximal ends are 
wide and deep, rather f.nr apart, and give to the section quite a pinched-in appearance. 
The axis of the guard is decidedly exceutric, and there seem to be two vascular grooves 
on each side, but on this point I am not quite satisfied. 
For some years now, lists and general notices of Australian Mesozoic fossils, 
including references of my own, have contained the name of Belemnitella diptifeha, 
McCoy. The meagre remsirks made by Sir F. McCoy on this Belemnite make it very 
diflicult to recognise the species ; but his comparison with Belemnitella plena, of the 
European Chalk, renders it much more easy of accomplishment. B. diptycha is said to 
differ from B. plena by being larger, the dorsal furrows a little farther apart, and the 
absence of a ventral furrow. I had provisionally named the specimens, PI. 35, figs. 7-9, 
Belemnitella McCoy, but was always much perplexed bythe absenceof the ventral 
groove on which the generic separation between Belemnites and Belemnitella is chiefly 
based. I have recently been favoured by Sir F. McCoy with the specimen on which be 
based the name, and to my surprise found it to be only a fragment of the distal end of 
a guard, indistinguishable from Tate’s Belemnites Canhami. Under these circumstances, 
the one must be considered as a synonym of the other, and taking into consideration the 
excellent description of Professor Tate, accompanied by a comprehensive figure, we 
cannot do less than accept his name, in preference to the hardly diagnosed species of 
McCoy. 
