*Images in development
Galeommatoidea/Neoleptonidae
Elliptical shell, gaping widely along the entire ventral margin. Sculpture of dense divaricating riblets (Free-living)
Galeomma turtoni
Shells not gaping, sculpture primarily commarginal
RV with single anterior and posterior radiating "lateral" flanges widely separated by ligament inserted into the umbonal cavity, no obvious resilifer. Left valve with lateral teeth as extensions of the dorsal margins
Hinge not of this arrangement
Shell transversely subovate, posterior subtruncate not markedly narrower than anterior
Shell obliquely subovate, posterior narrowly rounded, markedly narrower than anterior
External macro-sculpture other than incremental lines
External sculpture of incremental commarginal lines only
Radial elements present in shell or periostracum
Punctate or anastmosing commarginal elements present
Ligament set in a posterior oblique resilifer or on resilial ridge, posterior lateral teeth absent
Ligament on a median or posterior resilifer, posterior lateral teeth present
Outline subelliptical, L>H, beaks towards the posterior, ligament on a raised resilial ridge resembling a posterior tooth
Outline subquadrate to subovate, beaks at or behind the midline, ligament on a shallow sunken resilifer
Outline subquadrate, expanded anteriorly, anterior broadly truncate with Leptosynapta spp.
Devonia perrieri
Outline roundly subovate, oblong or subovate-trigonal, beaks close to the midline
Outline oblong, equilateral, surface obscured by heavy brown deposit, with Phascolion strombi inside Turritella and Apporhais shells
Montacuta phascolionis
Outline inequilateral, beaks behind or just behind midline
Outline obliquely oval to roundly subovate beaks behind midline
Outline subovate trigonal rather angular
Obliquely oval, radially striated, attached to spines of Spatangus and Echinocardium
Montacuta substriata
Anterior a little broader than posterior, sloping away at anterior dorsal margin, abyssal attached to Aeropsis
Kelliola symmetros
Anterior dorsal margin concave, microscopically radially striated
Scacchia tenera
Anterior dorsal margin sloping, lacking microsculpture
Scacchia sp.
[Taxon under review]
Ligament on a shallow depression in the hinge plate beneath the beaks
Ligament in a deep depression interrupting the hinge plate behind the cardinal teeth
Hinge with a hooked cardinal in LV and corresponding socket in RV, subcircular shell with fine regular commarginal ridges
Neolepton sulcatulum
Hinge with simple cardinal teeth, obliquely oval shell not exceeding 1.5mm
Altenaeum dawsoni
A single discreet cardinal in each valve
A single discreet cardinal in RV only
Outline rounded subquadrate, cardinals projecting, microscopic pits present on teleoconch
Hemilepton nitidum
Outline subcircular, not exceeding 1.6mm, cardinals low, attached to the tanaid Apseudes
Arculus sykesi
RV with strong anterior and posterior laterals with sockets into which fit the LV laterals, associated with sipunculans
Epilepton clarkiae
Lateral teeth poorly developed, LV as marginal extensions
