286 
INFERIOR OOLITE AMMONITES. 
— from which arose the more compressed form, Catull. aratum. (See, however, 
page 277.) None of the species of Gatulloceras can be considered senile; and 
it is highly probable that they gave rise to further mutations. 
Postscript. — Genus Dumortieria. — It was in 1885 that Dr. Haug applied this 
name to a certain section of Ammonites (see p. 231, et seq.) ; but lately Mr. Charles 
Upton has drawn my attention to its prior use, which Dr. M. C. Cooke has kindly 
confirmed, saying " it has been recognised as a genus of Hepaticse or liverworts 
from 1824 to the present." 
It would appear to have been the intention of the British Association 
Committee that the same generic name should not be used in zoology and botany ;^ 
but this rule seems not to have been followed of late years. Many biologists, so 
Prof. Rupert Jones tells me, do not consider it at all necessary to change a generic 
term given to an animal if it be found to bave been given to a plant. Under these 
circumstances I make no change in this generic name, but merely draw attention 
to the double use of the name Dumortieria, which I have already communicated to 
Dr. Haug. 
FamMy— AM AhTBmBM, Hyatt. 
1867. Amaltheoid^, Hyatt. Fossil Cephalopods ; Bull. Mus. Comp. Zool., 
No. 5, p. 89. 
Amaltheid^ (pars) auctorum. 
This family was originally proposed by Hyatt to contain the genera Amaltheus 
and Pleuroceras. It was afterwards extended by various authors to include a 
heterogeneous polygenetic series of Ammonites — in fact, all those of disc-like shape 
or possessed of a crenulate carina. Neither of these features, however, indicates 
any family affinity on the part of its possessors — in fact, the disc-like form is, 
plainly, the senile metamorphosis of the most widely-divergent phylogenetic series. 
I restrict the family Amaltheidse to include only the genera Amaltheus and 
Pleuroceras, together with a group of genera having affinity with Sonninia. The 
genera thus grouped together are derived from a common source. They also seem 
to fall naturally into two main sections ; to which for the convenience of reference, 
it is desirable to apply separate names. I propose, therefore, to divide the family 
into two sub-families : 
1 ' Eeports,' vol. xi, p. 115, § 10. 
