HATCHER: OSTEOLOGY OF HAPLOCANTHOSAURUS 39 
may, as I have already remarked, pertain to the first dorsal. I do not think it at 
all probable that more than one dorsal is missing from the series in HZ. utterbacki and 
it is with a feeling of considerable confidence that I place the number of dorsals in 
this species at least, at fourteen. Fully realizing the character of the evidences | 
upon which I have arrived at this conclusion | have spared no pains to present to 
the student all the evidence furnished by the material at my command, both as 
regards its anatomical characters and the position in which the different bones were 
found in the quarry. Aided by the accompanying diagrams and with the type 
material at his disposal the future student will be in full possession of all the evi- 
dence in the case and will therefore be in a position to decide for himself as to the 
worth of my conclusions. 
In placing the number of free dorsals at fourteen I am fully aware that this is a 
considerable advance over the number that has of late come very generally to be 
considered as characteristic of other members of the Sauropoda (Diplodocus, Bronto- 
saurus, Morosaurus). Considering however the less specialized nature of the present 
genus and the great differences seen, in other important characters, when compared 
with the genera just mentioned I do not consider this increase in” the number of 
dorsals as at all remarkable, for it is not at all Impossible that the earlier ancestors of 
Diplodocus, Brontosawrus and Morosaurus were provided with an equal number of 
free dorsals and that the reduction to ten in each of those genera may be regarded 
as a specialized character attendant upon and which took place along with that re- 
markable specialization which, as is well known, they must have undergone in other 
respects and which is most marked in that exceedingly complicated arrangement of 
laminz and buttresses seen in the dorsal and cervical vertebree of those genera. 
It will doubtless have been remarked that in describing the cervicals I have 
placed the number of vertebrz of this region at fifteen, the number present in Dzplo- 
docus. It must be admitted, however, that the material at hand does not afford a 
very reliable basis for determining the number of cervicals and I should not be at 
all surprised if the actual number of cervicals in Haplocanthosawrus should prove to 
be one or two less than in Diplodocus. In placing the number at fifteen, as in the 
latter genus, I assume that Haplocanthosawrus was provided with four more pre- 
sacrals than was Diplodocus. While my estimate of the number of cervicals in the 
present genus may prove to be too great, it is hardly possible that it will be reduced 
by more than two. This would still give to Haplocanthosaurus two more presacrals 
than are present in Diplodocus. It would thus appear that in the various genera of 
the Sauropoda the number of presacrals differed and that the number of cervicals is 
not entirely dependent upon an increase or decrease in the number of dorsals in any 
