genus B

New genus B Korn & Hairapetian (in press) Diagnosis Genus of the new family to be described by Korn & Hairapetian (in press) with a subinvolute conch. High coiling rate; whorl profile rounded rectangular, weakly depressed with concave venter. Without sculpture. Suture line with shallow external lobe and broadly rounded lateral lobe; without annular process (from Korn & Hairapetian in press). Type species New species H to be described by Korn & Hairapetian (in press); original designation. Included species NW Iran (this paper): new genus B to be described by Korn & Hairapetian (in press) hebes sp. nov., Wuchiapingian. Central Iran (Korn & Hairapetian in press): new species H to be described by Korn & Hairapetian (in press), Wuchiapingian. Remarks According to Korn & Hairapetian (in press), the new genus B is difficult to confuse with any other genus of Palaeozoic nautiloids because of its peculiar conch morphology with the box-shaped whorl profile, concave venter, skid-like ventrolateral shoulder, subparallel flanks and flattened umbilical wall. The new genus A to be described by Korn & Hairapetian (in press) differs from the new genus B to be described by Korn & Hairapetian (in press) by its clearly convergent flanks, resulting in a much narrower venter; it has an angular ventrolateral shoulder and an angular umbilical margin. Pseudotitanoceras also has convergent flanks and is characterised by a row of nodes on the ventrolateral shoulder and sometimes also at the umbilical margin (Shimansky 1965b: 163).