323 Dr. T. Wright on new Species of Echinodermata 



near Pewsdown, Gloucestershire, and near Burford, Oxon; it has 

 likewise been found near Minchinhampton : as far as we know, 

 it appears to be a Great Oolite species. 



We dedicate this species to our friend Mr. S. P. Woodward, of 

 the British Museum, to whose kindness we are much indebted for 

 the privilege of comparing our specimens with the magnificent 

 series of Echinodermata under his care, and which he has ren- 

 dered so valuable for reference by a systematic classification and 

 a correct nomenclature. 



Nucleolites Michelini, Wright. PI. XII. fig. 6, a~c. 



Test circular or oblong, discoidal and much depressed, posterior 

 border produced, truncated and slightly deflected in old in- 

 dividuals ; ambulacral areas narrowly lanceolate ; pedal pores 

 closely set together, vertex and apical disc nearly central ; 

 anterior half of the dorsal surface convex^ posterior half much 

 declined from the vertex to the posterior border; anal valley 

 narrow above, diverging below, extending from the apical disc 

 to the border ; base flat, slightly concave ; mouth excentral, 

 margin with five small lobes ; postero-lateral interambulacral 

 areas slightly tumid at the base. 



Height -j^ths of an inch, antero-posterior diameter 3 inches 

 and 2%ths, transverse diameter 2 inches and y%ths of an inch. 



Description. — The outline of this Urchin varies in difi^erent 

 individuals, and it likewise varied at different periods of life in 

 the same individual ; its most typical form is oblong, convex an- 

 teriorly, produced and truncated posteriorly, and swollen out in 

 the region of the postero-lateral interambulacra ; in others the 

 circumference is nearly circular, and in some it is transversely 

 oval ; the first form is we think characteristic of adult life, as the 

 production and truncation of the single interambulacrum were 

 markedly shown in the only two large specimens of this rare 

 species which we have seen ; in all the test is very flat, the ante- 

 rior half is gently and nearly equally convex, the posterior half 

 is-sloping and much declined in the direction of the posterior 

 border. The ambulacral areas are narrow, the anterior one most 

 so; the antero-lateral and postero- laterals are about the same 

 width, they have a lanceolate form, and are composed of very 

 narrow plates ; about y%ths of an inch above the margin, the 

 pores slightly diverge from each other, and continue apart until 

 they approach the apical disc ; the distance between the rows of 

 pores in this species is less than in any other Nucleolite of the 

 same size we know, and forms one of the characters by which it 

 is distinguished from its congeners ; the ambulacral areas are 

 likewise slightly elevated above the general surface of the test in 



