WHITE-TAILED TROPIC BIRD. 
would only be regarded as of subspecific value, but when dealing with Ancient 
Forms such as the present, these must be given higher value. I therefore 
regard it as a valid species, as the Ascension Island birds scarcely seem to 
differ in any details save measurements from those of the Pacific Ocean. 
Leptoph^thon lepturus (Daudin). 
Atlantic, Indian and Pacific Oceans. 
I recognise one subspecies at present from each Ocean, but series would 
probably enable the differentiation of more. 
Leptoph.®thon lepturus lepturus (Daudin). 
Mauritius ; Rodriguez. 
As synonyms should be noted : Phceihon candidus Temminck, Phmthon 
albus Schinz and Brodtmann, Phcethon flavirostris Brandt and Phcethon edwardsii 
Brandt. 
Leptophjethon lepturus dorothe.® Mathews. 
Queensland ; Pacific Ocean. 
Differs from L. 1. Upturns Daudin in its smaller size throughout. Measure- 
ments : Cuhnen 41-47; wing 246-271; tail, 101-111; middle toe 26.5- 
29 mm. Ditto of L. 1. Upturns Daudin from Mauritius : cuhnen 48-51 ; wing, 
269-282 ; tail 116-121 ; middle toe 29-32 mm. The bird with the longest 
wing from the Pacific Ocean, viz. 271 mm., has a bill measuring 43 mm. only, 
and the bird with the shortest wing from Mauritius, viz. 269 mm., has the bill 
48 mm. 
Rodriguez birds seem slightly smaller than typical Mauritius ones ; cuhnen 
46-51 ; wing 264-273 ; tail 118-121 ; middle toe, 31-33 mm. 
Leptophjethon I.EPTURUS ASCENSiONis, subsp. n. 
Ascension Island (type) ; Fernando Noronha. 
Ascension Island birds differ from typical P. 1. Upturns Daudin in their 
smaller wing measurement, though otherwise fairly agreeing. Cuhnen 47- 
51 ; wing 256-267 ; tail 102-111 ; middle toe 29-31 mm. These differ^ from 
the preceding in their slightly longer bills and middle toe. 
Three birds from Fernando Noronha give : culmen 46-49 ; wing 262-270 ; 
tail 113-119 ; middle toe 30-31 mm. 
The tail measurements throughout are for the tail without the two central 
feathers. 
The bird figured and described is the type, collected near Cairns, Queensr- 
land, in October, 1906. 
311 
