He described a number of new species collected from Jean-Baptiste Charcot's Antarctic expeditions.
The following species are named after Hallez:
Timea hallezi (Topsent, 1891)
Procerastea halleziana (Malaquin, 1893)
Scaptognathus hallezi (Trouessart, 1894)
Obrimoposthia hallezi (Böhmig, 1908).The genus Hallezia Sand, 1896 (Protozoa) is also named after him.