78 Dr. T. Wright on Fossil Echinoderms 



Description. The specimen before us is so much injured on 

 the dorsal surface, that we are unable to give a detailed descrip- 

 tion of this species, which appears to be not uncommon at Malta. 

 The ambulacral areas are narrow; the pores lie in contracted 

 zones, and the pairs are unconnected by sulci ; the avenues ex- 

 tend more than half-way down the sides of the test ; the dorsal 

 surface is elevated and convex, rounded before, and sloping gra- 

 dually from the vertex to the posterior border ; the apical disc 

 is very excentrical, and placed near the anterior border ; the cir- 

 cumference of the test is of an irregular oblong figure, round 

 before, flattened on the sides, and produced behind : the base is 

 undulated by the elevations of the interambulacra and the de- 

 pressions of the ambulacral areas ; the single interambulacrum 

 is prolonged backwards, and is truncated at the sides and at the 

 posterior border, which gives it a caudate form. The mouth 

 is nearly central, and is sunk in a deep depression; it is 

 transversely oblong, and is surrounded by five oral lobes, 

 having five petaloidal depressions of the ambulacral areas, with 

 three pairs of pores in each petal between them; the anus is 

 larger than the mouth-opening, and is situated at the inframar- 

 ginal border of the caudate process of the interambulacrum ; it 

 has a transversely oblong form, and is more convex before than 

 behind. The Urchin figured by Grateloup is much larger than 

 the Maltese specimens that have come under our notice ; but 

 the central mouth-opening and the form of the interambulacrum 

 induce us to think that it is only a gigantic variety of E. Richardi, 

 and not E. Kleinii, as supposed by Desmoulins. The identity of 

 this species with Klein's Scutum ovatum Issyaviense may or may 

 not be correct, as the figures of fossils in that work are not in 

 every case to be depended on. 



Affinities and differences. E. Richardi has some resemblance 

 to E. Kleinii, but the narrow ambulacral areas, the flattened 

 sides, and produced caudate interambulacrum in E. Richardi 

 afford points of distinction by which these allied forms may be 

 readily distinguished from each other. In E. Kleinii the base is 

 more concave, the mouth nearer the anterior border, and with 

 larger oral lobes than in E. Richardi, The dorsal surface presents 

 other points of difference : in E. Kleinii the posterior half of the 

 test is the most elevated, whilst in E. Richardi it slopes rather 

 abruptly downwards from the vertex to the truncated posterior 

 border. 



Locality and stratigraphical range. It was collected from bed 

 No. 2, at Malta; the specimen before us is the only one in 

 Earl Ducie's cabinet. The Geological Museum in Jermyn Street 

 possesses an interesting series of this form, which are all from 

 the same island. Grateloup found the large variety at Dax, in 



