Echinocyamidae, Lambert & Thiery, 1914

Ziegler, Alexander, Lenihan, Jennifer, Zachos, Louis G., Faber, Cornelius & Mooi, Rich, 2016, Comparative morphology and phylogenetic significance of Gregory’s diverticulum in sand dollars (Echinoidea: Clypeasteroida), Organisms Diversity & Evolution (New York, N. Y.) 16 (1), pp. 141-166 : 154

Echinocyamidae

The miniaturized sand dollars of the Echinocyamidae are represented here by six species belonging to two genera. The available dissection, MRI, and X-ray imaging data for Echinocyamus ( Fig. 2n, o ) and Mortonia ( Fig. 2p ) show that Gregory’ s diverticulum is lacking in echinocyamids.

Figures

Fig. 2 Absence of Gregory’s diverticulum in the Clypeasteridae (a–f), Laganidae (g–m), Echinocyamidae (n–p), Fibulariidae (q, r), and the miniaturized rotulid Fibulariella (s, t). This figure shows selected X-ray images, virtual MRI sections at the level of the main digestive tract, as well as a drawing and a photograph of dissected specimens. a, b Clypeaster reticulatus (24 mm test length); c Ammotrophus cyclius (35 mm); d, e Arachnoides placenta (27 mm); f Fellaster zelandiae (47 mm); g, h