The Albian-Cenomanian genus Allomma comprises reasonably distinctive echinoids whose interambulacral plating changes markedly at the ambitus - interambulacral plates possessing solitary primary tubercles above the ambitus (the adapical surface) and multiple primary tubercles below (the adoral surface).  A. wrighti is distinguished by a broad and flattened adapical surface (weakly conical for other species of Allomma) with a near absence of ambulacral primary tubercles.  Specimens are recorded from the Grey Chalk of SE England.

1).  Adoral view of an exceptionally preserved individual, retaining a largely complete compliment of articulated spines (x1.2, Grey Chalk, Folkestone, Kent, BMNH (British Museum (Natural History) London) E1084.  Image © 2007 The Natural History Museum, by kind permission.

2).  Adapical view of an isolated test from the Grey Chalk near Dover, Kent (x4.0, BMNH (British Museum (Natural History) London) EE1295.  Image © 2007 The Natural History Museum, by kind permission.

3).  Detail of Fig. 1, showing primary spines (x2.5).  Image © 2007 The Natural History Museum, by kind permission.

4).  Detail of Fig. 1, showing the adoral surface of the test, with elements of the lantern protruding through the peristome (x2.5).  Image © 2007 The Natural History Museum, by kind permission.