it was not the first Helicoprion species to be described, it was the first known from complete tooth whorls, demonstrating that Helicoprion was distinct from Edestus. As a result, H. bessonowi serves as the type species for Helicoprion. H. bessonowi is primarily based on a number of specimens from Artinskian-age limestone of the Divya Formation, in the Ural Mountains of Russia. H. bessonowi specimens are also known from the Tanukihara Formation of Japan and Artinskian-age strata in Kazakhstan. It can be differentiated from other Helicoprion species by a short and narrowly spaced tooth whorl, backward-directed tooth tips, obtusely-angled tooth bases, and a consistently narrow whorl shaft. One of two Helicoprion species described by Wheeler in 1939, H. nevadensis, is based on a single partial fossil found in a Nevadan mine by Elbert A. Stuart in 1929. This fossil, UNMMPC 1001, has been lost. It was reported as having originated from the Rochester Trachyte deposits, which Wheeler considered to be of Artinskian age. However, the Rochester Trachyte is in fact Triassic, and H. nevadensis likely did not originate in the Rochester Trachyte, thus rendering its true age unknown. Wheeler differentiated H. nevadensis from H. bessonowi by its pattern of whorl expansion and tooth height, but Leif Tapanila and Jesse Pruitt showed in 2013 that these were consistent with H. bessonowi at the developmental stage that the specimen represents. Based on isolated teeth and partial whorls found on the island of Spitsbergen, Norway, H. svalis was described by Stanisław Siedlecki in 1970. The type specimen, a very large whorl with specimen number PMO A-33961, was noted for its narrow teeth that apparently are not in contact with each other. However, this seems to be a consequence of only the central part of the teeth being preserved, according to Tapanila and Pruitt. Since the whorl shaft is partially obscured, H. svalis cannot be definitely assigned to H. bessonowi, but it closely approaches the latter species in many aspects of its proportions. With a maximum volution height of , H. svalis is similar in size to the largest H. bessonowi, which has a maximum volution height of . H. ergassaminon Like H. davisii, Helicoprion ergassaminon is known from the Phosphoria Formation of Idaho. However, it is comparatively much rarer. H. ergassimon was named and described in detail within a 1966 monograph by Svend Erik Bendix-Almgreen. The holotype specimen ("Idaho 5"), now lost, bore breakage