_Parus_, LINNÆUS, Syst. Nat. 1735. (Type, _P. major_.)
GEN. CHAR. Head not crested. Body and head full. Tail moderately long,
and slightly rounded. Bill conical, not very stout; the upper and
under outlines very gently and slightly convex. Tarsus but little
longer than middle toe. Head and neck generally black or brown, with
sides white. Nest in holes. Eggs white, sprinkled with red.
In the group, as defined above, are embraced several genera of modern
systematists. The true black-capped American Titmice belong to the
section _Pœcile_ of Kaup, and exhibit but three well-marked forms;
one, _P. montanus_, with a white stripe over the eye; one,
_atricapillus_, without it, with black head; and one, _hudsonicus_,
also without it, and with brown head. The species may be arranged as
follows:—