Rotulidae, Gray, 1855

Rotulidae View in CoL

Data were available for the three rotulid genera Heliophora , Rotula , and Rotuloidea as well as the closely related Fibulariella . The three extant species Fibulariella acuta ( Fig. 2s, t View Fig ), Heliophora orbicularis ( Fig. 3a, b View Fig ), and Rotula deciesdigitatus ( Fig. 3c–e View Fig ) do not possess Gregory’ s

Jacksonaster depressum ( 28, 32 mm); i, j Laganum laganum ( 28 mm); k, l Peronella lesueuri ( 26 mm); m Peronella orbicularis ( 21 mm); n, o Echinocyamus pusillus (5.5, 5 mm); p Mortonia australis ( 13 mm); q Fibularia ooulum (5.5 mm); r Fibularia nutriens ( 11 mm); and s, t Fibulariella acuta (6.5, 7 mm). r Modified from Clark (1909). All images show an aboral view with ambulacrum III facing upwards. go gonad, in intestine, re rectum, st stomach. Scale bar a–m = 5 mm and n–t = 1 mm

diverticulum. The available data suggest the same for the fossil genus Rotuloidea , although several of the X-rayed specimens were missing Aristotle’ s lantern. Relatively comprehensive Xray imaging series are available for the extant species H. orbicularis ( 6–78 mm) and for the fossil Rotuloidea ( 11– 40 mm). These data further support the conclusion that rotulids as well as Fibulariella do not possess Gregory’ s diverticulum.