Sir Algernon Phillips Withiel Thomas KCMG (3 June 1857 – 28 December 1937) was a New Zealand university professor, geologist, biologist and educationalist. He was born in Birkenhead, Cheshire, England in 1857 and died in Auckland, New Zealand in 1937. He is best known for his early research (1880–83) into the life cycle of the sheep liver fluke (Fasciola hepatica), a distinction he shared with the German zoologist Rudolf Leuckart, and for his report on the eruption of Tarawera (1888).
Thomas was born in Birkenhead, Cheshire, on 3 June 1857, the sixth child and second son of Edith Withiell Phillips (1826–1909) and her husband John Withiell Thomas (1823–1909), an accountant and, later, senior partner in the Manchester practice Thomas, Wade, Guthrie & Co. Both his parents emanated from Redruth in Cornwall. His elder brother Ernest Chester Thomas, (1850–1892), a Gray's Inn barrister by profession, obtained early recognition as Librarian of the Oxford Union (1874) and, subsequently, for his work as secretary of the Library Association of the United Kingdom (1878–1890) and for his 1888 edition of The philobiblon of Richard de Bury. Two of his elder sisters, Clara Irene Thomas (1852–1919) and Lilias Landon Thomas (1854–1929), actively promoted secondary education for women, notably as foundation headmistresses respectively of Sydenham High School (1887) and Edgbaston Church of England College for Girls (1886).
In 1861, Thomas' family moved to Manchester where he was educated privately before being sent as a boarder to Ockbrook School in Derby. He subsequently followed his brother to Manchester Grammar School. Inclined to scientific studies from an early age, Thomas profited from his attendance at Manchester Grammar during the regime of its reforming high master, Frederick Walker who had a reputation for ensuring that his pupils achieved the highest academic distinctions. Awarded a Brackenbury Natural Science Scholarship by Balliol College, he matriculated at Oxford on 20 October 1874, aged 17. Studying under Robert Clifton (physics), Henry Smith (mathematics), Joseph Prestwich (geology), WW Fisher (chemistry), Henry Acland (human anatomy) and George Rolleston (biology), he obtained a second in mathematical honour moderations in 1876 and a first in natural sciences in the honour finals in 1877, taking his BA in 1878. In 1879 he was awarded a Burdett-Coutts scholarship in geology, undertaking post-graduate study in Italy (Stazione Zoologica, Naples), France, Switzerland and Germany (Philipps-Universität Marburg). He took his MA in 1881.