106 ON AN EXTINCT MAMMAL. 
wherein determination of the kind seems justified by reason, but 
even in them the argument scarcely carries us over the misty valley 
between the possible and probable. Natural association is for the 
present our only safe guide to the actual. 
TABLE OF MEASUREMENTS: 
mm, 
Upper Morar SERtES—length : : : - oh USE 
Premolar—length . . : : $ ‘ : : 15 
Premolar—breadth 5 F : : ‘ ; ; 145 
Penultimate Molar—length . ; ; : P : 38 
Penultimate Molar—breadth : : : : ; 20% 
Incisor—length at inner fore angle ; : : / 55 
Incisor—length of basal section . : , j : 31 
Incisor—breadth of basal section . . . ‘ : 20.5 
Second Incisor—breadth of crown ; - : : 7-5 
Second Incisor—length of crown. : - : ; 8 
Lower Morar SERIES—length ‘ é : ; ce LGN 
Premolar—length . : : d : ; ; 14.5 
Premolar—breadth : 4 ? ; ; ; : 8.5 
Penultimate Molar—length . ; : . ; : 34.5 
Penultimate Molar—breadth . f : : : : 22 
Incisor-—length at inner fore angle : : : : 50.5 
Incisor—length at base : : i : : - 32 
Incisor—breadth at base : : 3 : ; : 20.5 
ManpistE—total length . : ; : - ; = 440 
Depth at premolar ; , : ; : : + 105.5 
Depth at condyle . : : : F : > s 109 
Length of diastema A : 2 A ; ; : 7o 
CraNiuM—total length . ‘ ; . ; : « 523 
ON AN ACARUS ASSOCIATED 
WITH A DISEASED CONDITION MA tae 
BANANA, 
HENRY TRYON. 
(Read on 5th August, 1887.) 
Upon a specimen of the banana plant forwarded some weeks 
since by the secretary of the East Moreton Farmer’s Association 
to the museum for examination, and described as “‘ Young plant 
and old root—-the rust,” the objects exhibited were procured. 
These are male and female examples of a minute mite belonging 
to the family Sarcoptidz and to the tribe which Mr. Mégnin has 
