Oates included the Titmouses in the same family as the Crows and the group of birds he called Crow-Tits. Whilst, however, they show certain affinities with both of these groups, the three seem to be much easier to separate than are many others, such as the Thrushes, Flycatchers and Warblers, the true Shrikes, etc., and it, therefore, seems to be more consistent to keep these separate also.
The Titmouses, Paridae, differ from the Corvidae in having the first primary equal to or less than half the length of the second, whereas the latter have this always more than half as long as the second.
Like the Corvidae, the Paridae have the nostrils concealed by feathers or bristles, though in the genus Melanochlora the soft feathers which lie over the nostrils do not wholly cover them. The bill is short and conical, varying considerably in depth and stoutness ; the rictal bristles are short, the tarsus well developed and the surface scutulated; the wing is generally weak and rounded but is longer and more pointed in Melanochlora.
Hellmayr has divided the Titmouses into several subfamilies, and includes amongst them the Paradoxornithidae. These latter birds, however, seem to me to constitute a good family, showing in some respects an affinity to the Titmouses, but in others a still closer connection with the Timeliidae. The genus Panurus, the Bearded Tits, should probably also be placed with the Paradoxornithidae.
As regards the Indian Titmouses, 1 see no reason to divide them into subfamilies, and I include them all in the same. Since, however, the ' Fauna of India' was published, we have had to add other genera and species to our list, the principal being Remiz (Anthoscopus) coronatus and Parus (Cyanistes) cyanus.
The key to the genera given below applies only to our Indian species. Hellmayr includes Lophophanes, Sylviparus, Machlolophus and Cyanistes in the genus Parus, but though Cyanistes cannot be divided from that genus, the other three appear to me to be generically distinct and are therefore retained. Lophophanes, it is true, is not always crested. Our Indian Lophophanes ater aemodius has a well-developed crest, although it is only a subspecies of L. ater ater which has none and the two extremes are linked up by geographical races which have crests in varying degree. On the other hand, the shape of the tail in this genus quite suffices to keep it distinct from Parus.
Cyanistes is a true Parus in everything but colour. The young are like the adult but pder, and in some species the grey or black in the adult is strongly suffused with green in the young.
Key to Genera.
A. Tail slightly rounded.
a. Head not crested.
a1. Outermost tail-feathers falling short of .the tip of the tail by length of
hind claw only PARUS, p. 73.
b1. Outermost tail-feathers falling short of the tip by length of hind toe and
claw AEGITHALISCUS, p. 93.
b. Head crested.
c1 Wing never as much as 90 mm MACHLOLOPHUS, p. 89.
d1. Wing never as short as 100 mm MELANOCHLORA, p. 101.
B. Tail square or very slightly forked.
c. Head crested LOPHOPHANES, p. 83.
d. Head not crested.
e1. Plumage above yellowish green SYLVIPARUS, p. 88.
f 1. No green on upper plumage REMIZ, p. 100,