. Annual report - Western Society of Malacologists. Mollusks; Mollusks. Reproducti\'e behavior (egg laying) was most pro- nounced durini; March to June. THE SHAPE OF TESSAROLAX, AN UNUSUAL LATE CRETACEOUS GASTROPOD LouElla R. Saul ln\crtcbaite Paleontology Section Natural History Museum of Los Angeles County Los Angeles. California 90007 Characteristic morphology can now be described for typical Tessarolax Gabb, 1864, based on more complete specimens, especially of Tessarolax incnis- taia Anderson & Hanna, 1935, of early Maastrichtian age from northern Baja California, Mexico. Gabb based t
. Annual report - Western Society of Malacologists. Mollusks; Mollusks. Reproducti\'e behavior (egg laying) was most pro- nounced durini; March to June. THE SHAPE OF TESSAROLAX, AN UNUSUAL LATE CRETACEOUS GASTROPOD LouElla R. Saul ln\crtcbaite Paleontology Section Natural History Museum of Los Angeles County Los Angeles. California 90007 Characteristic morphology can now be described for typical Tessarolax Gabb, 1864, based on more complete specimens, especially of Tessarolax incnis- taia Anderson & Hanna, 1935, of early Maastrichtian age from northern Baja California, Mexico. Gabb based the aporrhain gastropod Tessarolax on a speci- men of early Campanian (Late Cretaceous) age col- lected at Tuscan Springs. Butte County. California, from which the labral extensions were broken. Despite the incompleteness of original and subsequent speci- mens of the type species, Tessarolax distorta Gabb, 1864, the genus has been recognized in Europe, India, and Japan. Tessarolax has four long curving digitations (1-4) extending from its aperture. Two sprout from the outer lip edge; one extends along and beyond the spire, and the fourth engulfs and extends beyond the ros- trum. The posterior outer lip digitation (1) slopes toward the substrate, bends posteriorly, and turns away from the substrate near its distal end. The chan- nel along the digitation begins on the apertural side, but migrates to the abapertural side. The distal third of the digitation, but not including the final upward por- tion, is flattened and appears abraded on the substrate side. The anterior outer lip digitation (2) slopes more abruptly toward the substrate, then more abruptly reverses slope and bends upward. The channel in the digitation begins on the apertural side, runs along the anterior side of the digitation at the bend, then migrates back to the labral side along its upturned portion. A rounded, thick callus pad that is abraded on its substrate side embellishes the bend. The rostral digitation (3
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