The shell is small, in the adult stage averaging about 62 mm (2.4 in) in length, against 90 to 110 mm (3.5 to 4.3 in) in length for the fully adult carpenteriana. It is proportionately much heavier, the anal fasciole is more strongly constricted, and the appressed margin of the whorl does not approach as closely to the periphery of the preceding whorl as in that species. The periphery is often marked by a minutely beaded or undulate thread, and is more nearly midway between the sutures on the spire than in carpenteriana. The aperture is shorter than the spire in nearly every case, while the reverse is true of carpenteriana.
(description of Bathytoma tremperiana compared with Bathytoma carpentaria)[7]
^ abAuffenberg, Kurt (2021). Bieler R, Bouchet P, Gofas S, Marshall B, Rosenberg G, La Perna R, Neubauer TA, Sartori AF, Schneider S, Vos C, ter Poorten JJ, Taylor J, Dijkstra H, Finn J, Bank R, Neubert E, Moretzsohn F, Faber M, Houart R, Picton B, Garcia-Alvarez O (eds.). "Megasurcula carpenteriana (Gabb, 1865)". MolluscaBase. World Register of Marine Species. Retrieved 28 September 2024.
^Gabb, W.M. (1865). "Description of new species of marine shells from the coast of California". Proceedings of the California Academy of Sciences. 3 (3): 182–190.
