1014 MR. OLDFIELD THOMAS ON THE [Dec. 15, 
that the labour and time demanded would have rendered the pre- 
paration of the paper at all quite impossible, and partly because such 
diagnoses can never be really full and accurate unless prepared in 
connection with the working out of the species of each genus. 
Moreover, of all the groups he recognizes, Alston’s paper contains 
diagnoses, and it would be superfluous to repeat them here. 
Where I differ from his conclusions full reasons are given in the 
footnotes. 
Comparing the numbers of recent families and genera recognized 
in the two papers, we have 18 families in Alston against 21 now, 
the difference being due to the Lophiomyide being suppressed, and 
the Bathyergide, Heteromyide, Erethizontide, and Pedetidw added. 
Of genera Alston recognized 100, as against 159 now considered 
valid ; of the additional 59 just about half are formed by the breaking 
up of old genera and half are altogether new discoveries. 
Nomenclatural questions have of necessity cropped up here and 
there, and the recent work of American authors in this respect 
has been fully utilized. It is with the greatest regret that I have 
had to use a good many names unfamiliar to English naturalists, 
but the evidence in every case is so clear as to leave no room 
for doubt, and none are mere matters of opinion. Recognizing 
that the ultimate use of these names is inevitable, J think the 
sooner a knowledge of them is disseminated the sooner will the 
intermediate stage of confusion be passed through and done with. 
Where comparatively unfamiliar names are used, the better-known 
terms are placed in brackets after them, as also are any special 
synonyms which it seems of importance to mention. 
It should be again repeated that the special object of the list is 
the proper allocation of the genera in their respective subfamilies, 
and I have purposely been as conservative as possible with regard 
to the groups of higher rank, following Alston wherever there has 
not been very special reason for departing from his arrangement. 
In regard, however, to Anomalurus and Aplodontia, both placed 
by him in the Sciuromorpha, I have had to give in my adhesion to 
the views expressed by more recent authors, that these two aberrant 
genera cannot rightly be placed with the Squirrels. But where 
they should go is by no means clear—Winge, Zittel, and Tullberg 
. all differing in the matter; nor can I say that I agree with any 
one of them. As it seems a pity to abolish the convenient and 
time-honoured groups Sciuromorpha, Myomorpha, and Hystrico- 
morpha, just for the sake of these genera, I have thought it best 
to put each of them under a special group-name ’, leaving it for 
further research to show their true relationships. Fortunately, 
their serial position in the list, like that of Pedetes, may be left 
almost exactly as in Alston’s paper. 
1 T have purposely not used names ending in morpha, as, apart from the 
length and clumsiness of the resulting combinations, I do not think it at present 
advisable to consider the groups Anomaluri and Aplodontix as of the same 
rank as the Sciuromorpha and the others. 
