408 Mr. G. A. Boulenger on the 
Several species, among them our most common starfish 
(Asterias rubens), I have been unable to examine. The 
material of some of the species was rather scanty and was 
from a single locality only. This was the case with Bentho- 
pecten spinosus and Dytaster agassizi. ‘The specimens 
examined of these two species (see the table, p. 402) have a 
disc-radius of 5-10 mm. and 6-12 mm. respectively *, and 
seem to belong to the same year-class (group II.). The 
question regarding the age of the starfishes therefore needs 
further investigation. 
XL.—Synopsis of the American Species of Rana. 
By G, A. Boutenesr, F.R.S. 
(Published by permission of the Trustees of the British Museum.) 
I. Toes pointed or with slightly swollen tips. 
A. Glandular dorso-lateral fold absent or flat and ill-defined, or, if 
narrow and prominent, not extending to the hip; tympanum 
at least 2 diameter of eye, usually much larger, especially in 
males; tibia 24 to 4 times as long as broad; toes } to entirely 
webbed; outer metatarsals separated by web nearly to the 
base; nasal bones in contact with each other or narrowly 
separated. 
1. Male with internal vocal sacs; dorso-lateral fold absent or 
flat and very indistinct. 
Vomerine teeth between the choane (rarely 
just behind them) ; first finger as long as 
or a little longer than second ; tibio- 
tarsal articulation reaching tympanum 
or eye; heels meeting or slightly over- 
lapping when the hind limbs are folded 
at right angles to the body; tibia 27; 
to 2: times in length from snont to vent ; 
tip of fourth toe free; no dorso-lateral 
BO sd ah ib sh A aces Vioittats hit estate ihe oot i R. catesbiana, Shaw. 
Vomerine teeth between the choane ; first 
finger a little shorter than second ; tibio- 
tarsal articulation reaching tympanum 
* The material of Benthopecten spinosus has not a maximum; of 
Dytaster agassizi, on the other hand, there is a marked maximum at 
9-10 mm. comprising 18 individuals (or 52°9 per cent. of the total 
number). 
a 
