In 1891, Gundlach offered six field-type lens formulae, five of which were rapid rectilinear types and one single achromatic type. They were the: Gundlach Rapid Rectilinear Lens, Gundlach Perigraphic Lens, Gundlach Wide Angle Lens, Gundlach Star Lens, Gundlach Star Wide Angle Lens and Gundlach Single Achromatic Lens.
References:
The American Annual of Photography and Photographic Times Almanac for
1888, C.W. Canfield, ed.; Scovill Mfg. Co. (New York, NY), copyright
1887, ads p. 15
The International Annual Anthony's Photographic Bulletin, Vol. I,
1889, W. J. Harrison
and A. H. Elliot, eds., E. & H. T. Anthony & Co. (New York, NY), ads
p. 37
Illustrated Catalogue of Photographic Lenses, Sixth Edition,
Gundlach Optical Co., (Rochester, NY), dated June 1891, p. 10
The Internation Annual of Anthony's Photographic Bulletin", Vo. IV,
June, 1891, E. & H.T. Anthony & Co. (New York, NY), ads p.67
Descriptive Catalogue and Price List of Photographic Apparatus,
E. & H.T. Anthony & Co. (New York, NY), November 1893, p.19
Illustrated Catalogue of Photographic Equipments and Materials for
Amateurs, E. & H.T. Anthony & Co. (New York, NY), February, 1898,
pp. 53-54
Illustrated Catalogue of Photographic Equipments
and Materials for Amateurs, E. & H.T. Anthony & Co. (New York, NY),
November, 1898, p. 48