Sorry about that, that's what I get for scanning.
Just searched in Logos under my STs and here is what I am seeing:
James Boyce, Abstract of Systematic Theology (Chapter 20, Creation of Man, Section 2 - The Unity of the Race)
The expression above, "the present race of men," was not intended to intimate a belief that there have been more races of men than one. This, however, has been contended for; but, while the possibility of other races before Adam or contemporaneous with him may he admitted, the unity of the present race and its common descent from Adam must be maintained. . . .
But so far as this is intended to deny the unity of the present race, and to declare that any portion of it is not of Adamic origin, it is directly contrary to the Word of God.
1. Because the Scriptures trace the race of men now existing back to Noah, and through him to Adam.
2. Because they teach also that all others, except the eight saved in the Ark, were destroyed by the flood. If any other races of men existed before that time, which is not probable, they must then have been destroyed with the others of the Adamic race.
3. They not only speak of all mankind in general as though of this one race, but declare expressly that God "made of one every nation of men for to dwell on all the face of the earth, having determined their appointed seasons, and the bounds of their habitation." Acts 17:26. The King James version has "Made of one blood." This is especially emphatic because spoken to the Athenians, who claimed a special, separate origin from others.
4. The Scriptures account for the universal sinful condition of men, by not only a representative, but natural relation to Adam.
5. Salvation from sin is offered through Christ as the second Adam, whose fitness for his work was secured, not only by his representative relation, but also by his assumption of the same nature with man. Therefore his genealogy in Luke is traced back to Adam. It was also to "the whole creation," Mark 16:15, that Christ commanded his gospel to be preached, and "of all the nations," Matt. 28:19, that he ordered disciples to be made.
Bavinck, Reformed Dogmatics, vol. 2 has a section on The Unity of the Human Race.
In Vol. 3 he has a section on inherited sin and says the following:
That racial and variant traits are propagated constantly is subject to legitimate doubt; undoubtedly races exist—also among humans—that persist century after century (the Indo-Germanic, the Semitic race, and others), but these races originally stemmed from the one human race. We do not know how, nor can we say with certainty that they will continue to exist in the future under very different circumstances.
Herman Bavinck, John Bolt, and John Vriend, Reformed Dogmatics: Sin and Salvation in Christ, vol. 3 (Grand Rapids, MI: Baker Academic, 2006), 112.
Geerhardus Vos, Reformed Dogmatics, ed. Richard B. Gaffin, trans. Annemie Godbehere et al., vol. 2 (Bellingham, WA: Lexham Press, 2012–2016), 20.
20. How does one prove the unity of the human race?
a) It is a generally accepted principle that the instances of the same species can have a common origin.
b) As a consequence of this, it is only necessary to show that the human races, notwithstanding all their diversities, form one species.
c) A species is determined by:
1. Organic structure. When differences in bodily organism appear for two animals that are not accidental divergences but apparently have a purpose, this difference proves difference of species. One does not find such differences among the human races. All points of difference between the races are accidental, not intentional.
2. Physiological characteristics, that is, everything related to the functions of the organism (blood circulation, digestion, etc., etc.). Even in this respect the human races do not show the slightest difference. They are physiologically alike.
3. Psychological predisposition. Neither here does a difference occur. All human races have the same mental capabilities.
4. The ability to procreate. Two species can frequently intermingle, but what is produced is infertile and does not reproduce. All human races can intermingle and still preserve their fertility in the offspring of this intermingling.
d) In addition, there is as well important linguistic evidence that counts not just for the possibility but also for the reality of common descent.
Berkhof has a section on the origin of man and the unity of the race
Charles Hodge, Systematic Theology, vol. 3 (Oak Harbor, WA: Logos Research Systems, Inc., 1997), 417–418.
It is in this as in many other cases. The Mosaic law discountenanced and discouraged intermarriage between the chosen people and their heathen neighbours. With regard to the Canaanites, such intermarriages were absolutely forbidden; with other heathen nations, although discountenanced, they were tolerated. Joseph married an Egyptian; Moses, a Midianite; Solomon married Pharaoh’s daughter. Such marriages, in the settled state of the Jewish nation, may have been wrong, but they were valid. Even now under the Christian dispensation, believers are forbidden to be unequally yoked together with unbelievers. It does not follow from this that every marriage between a believer and an unbeliever is invalid. These remarks are not out of place. The truth suffers from being misapprehended. If the Bible is made to teach what is contrary to the common sense, or the intuitive judgments of men, it suffers great injustice. No man can force himself to believe that a man’s marrying the sister of a deceased wife is the same kind of offence as a father’s marrying his own daughter. The Bible teaches no such doctrine; and it is a slander so to represent it.
Not sure if any of that is helpful.