Our probate courts are courts of limited jurisdiction, and therefore their decrees are not conclusive as to the fact of jurisdiction, but may be collaterally attacked for want of jurisdiction. Sears v. Terry, 26 Conn. 273; First Nat. Bank v. Balcom, 35 Conn. 351; Olmstead’s Appeal, 43 Conn. 110; Culver’s Appeal, 48 Conn. 165; Hartford v. Poindexter, 84 Conn. 121, 131, 132, 79 Atl. 79; Woodmont Asso. v. Milford, 85 Conn. 517, 523, 84 Atl. 307.

In respect of the appointment of guardians of the persons of minors under fourteen years of age, the jurisdiction is conferred by §§ 4861 and 4863 of the General Statutes, the material portions of which are printed in the foot-note for convenience of reference. In acting under statutes conferring jurisdiction, the probate [*205] courts have no powers except those which are expressly-granted and such other powers as are necessary to the exercise of the jurisdiction expressly conferred. Chamberlin’s Appeal, 70 Conn. 363, 378, 39 Atl. 734; De-Ladson v. Crawford, 93 Conn. 402, 405, 106 Atl. 326.

Section 4861 deals with the case of legitimate children having a parent or parents. Such parent or parents are declared by the statute to be the sole guardians, or joint guardians, as the case may be, of any legitimate minor child. Section 4863 covers the same ground as to illegitimate minors, saying: “The guardian of any [*206] child, and the mother of an illegitimate child, shall have the same duties and rights which by common law or statute are assigned to the sole surviving parent of such child.” That language constitutes the mother of an illegitimate child sole guardian of the person of such child.

Turning back to § 4861, the statute empowers the Court of Probate for the district in which the minor resides, to remove as guardian one or both of the parents, but only after such notice and hearing as the statute prescribes, and only upon a finding that either or both parents are unfit persons to have charge of the child or have abandoned or neglected to make suitable provision for the support or education of such child, or are not residents of the United States. The right of sole guardianship until so removed after such notice and such finding, is one of the rights conferred upon the mother of an illegitimate child by § 4863; and it is only “if both parents or the sole living parent shall be so removed” (§4861), that the Court of Probate is authorized to appoint a guardian of the person of a minor whose parent or parents are living.

The petitioner’s offer to prove that Dorothy Evermon was an illegitimate child having a mother living who was a resident of New Jersey, and that the decree appointing the respondent guardian of the person of Dorothy Evermon was made without notice to the mother and without proceedings to remove the mother as guardian,—was, therefore, an offer of evidence admissible to prove that the decree was wholly void for want of jurisdiction; and it follows that the Superior Court erred in excluding the evidence and in ruling that the decree of the Court of Probate was conclusive in this proceeding, and could not be attacked except on appeal or by proceedings for the removal of the respondent as guardian.

[*207] The proceeding in the Superior Court by writ of habeas corpus is a well-recognized summary method of settling controversies as to the custody of a minor. Kelsey v. Green, 69 Conn. 291, 37 Atl. 679; Dunham v. Dunham, 97 Conn. 440, 117 Atl. 504; Pfeiffer v. Pfeiffer, 99 Conn. 154, 121 Atl. 174.

The trial court ruled that the remedy by habeas corpus was not applicable in this case because the decree of probate stood in the way. This ruling prejudged the issue, for the petitioner offered to prove, and had the right to attempt to prove, that the decree was a nullity for want of jurisdiction to make it.

There is error, the judgment dismissing the writ is set aside, and a new trial is ordered.

In this opinion the other judges concurred.