84 Dr. T. Wright on Fossil Kchinoderms 



cornua of which approaches the anal opening ; below the fascicle 

 there is another group of small perforated tubercles and a 

 copious granulation ; the crescentic depressions, subanal fascicle, 

 and this group form together a triangle, the base of which lies 

 before the anus, and its apex points towards the mouth ; around 

 this opening five pair of short poriferous zones indicate the 

 termination of the ambulacral areas. 



Affinities and differences. The form of the ambulacral areas, 

 the shortness of the anterior poriferous zone, and the size and 

 depth of the areolar spaces around the cylinders of the large 

 tubercles, together with the carinated elevation in the middle of 

 the interambulacrum, form a group of organic characters which 

 sufficiently distinguish this species from its congeners. In Spa- 

 tangus Desmarestii, which is found with S. Hoffmanni in the 

 same beds in Westphalia, the size of the test, the absence of very 

 deep areolas on the dorsal surface, the equal length of the pori- 

 ferous zones of the anterior ambulacra, and the much smaller 

 tubercles at the base, easily enable us to distinguish it from 

 S. Hoffmanni. 



Stratigraphical range and localities. It is found at Malta in 

 bed No. 4, the calcareous sandstone, and in Westphalia ; it has 

 been collected from the Miocene at Doberg near Biinde, and at 

 Astrapp near Osnabruck. 



Spatangus De Koninckii, Wright, n. sp. 



Test cordate, depressed before, elevated behind by the develop- 

 ment of dorsal and basal median carinse on the single inter- 

 ambulacrum ; ambulacral areas short and broadly petaloid; 

 anteal sulcus slight; depression of the single ambulacrum 

 inconsiderable ; several large tubercles between the petaloidal 

 ambulacra; posterior border obliquely truncated downwards 

 and forwards ; anal opening large and circular ; basal tubercles 

 of moderate size ; basal portions of the postero-lateral ambu- 

 lacra form two smooth tracks destitute of tubercles between 

 the posterior border and the mouth. 



Dimensions. Antero-posterior diameter \-f V) inch ; transverse 

 diameter ly 4 ^ inch ; height at the interambulacrum ^ths of an 

 inch. 



Description. An imperfect specimen of this Urchin was at 

 first mistaken for a small variety of Spatangus Desmarestii, 

 Goldf., and entered under that name in the list of fossils from 

 bed No. 2. Having lately obtained a better specimen of this 

 form, we are now enabled to give a description of it, which will 

 be found to differ in many essential points from that species, to 

 which it was at first referred. The test is regularly cordate, 



