Hawkesworth's Coll.
of Voyages, 3 652.
Sooty Tern, Gen.Syn.6 352.Arc.Zool.2 Number 447.
There are two specimens of this bird in the collection, marked 12 a, and 12 b.
13.

Sterna pelecanoides (n.s.) S.alba; capitis vertice nigro albo-variegato; dorso, alis, caudaque canis; remigibus fusco-atris, rhachibus albis.
Colli latera parce cano-maculata; tectrices secundariae primoribus obscuriores; remiges fusco-atrae, pogoniis internis fere ad apicem albo-marginatis; rectrices externae fuscae basi apiceque albis; rostrum subflavum; pedes nigri.
Longitudo corporis, 19 1/4; alae a carpo ad remigem primam, 13 1/2; caudae, 6 3/4; rostri, ad frontem, 2 1/3, ad rictum, 3 1/6; tarsi, 1 1/6.
The hallux, or hind toe, of this bird appears to be more closely united to the fore toes, and to be situated more in front than is usual among the Terns: it is also to be observed, that the side of the nail of the middle toe is considerably dilated, although not serrated, similar to what is observed among the Pelecanidae.

These characters offer a corroboration of the affinity of the Sternae to the family of the Pelecanidae, and particularly to the genus Phaeton, which approaches the Terns more closely than any other group of that family, in the smaller size of the membrane that unites the toes (see Linnean Transactions 14 505).

It may also be stated on the other hand, that the same membrane of the Sterna pelecanoides deviates from its own genus, and approaches the Pelecanidae, in its being more dilated than usual.

The wings are longer than the tail for a considerable extent, by which our bird also evinces another character, in common with the long-winged Tachypetes, or Frigate bird.
14.