FIDDLE HEART-URCHIN. 



187 



ECHINID.E. 



SPATANGACEJE. 



Genus Brissus. Klein. 



Generic Character. — Body cordate, convex, having two sets of ambulacra, 

 dorsal and oral ; four of the dorsal ambulacra petaloid ; a dorsal impression in- 

 closing the ambulacra; sub-anal impression transverse, sub- inferior. 



FIDDLE HEART-URCHIN. 



Brissus lyrifer. Forbes. 



Specific Cliaracicr. — Body ovate ; a deep and narrow dorsal depression ; ambu- 

 lacra deep; dorsal impression fiddle- shaped ; post-oral spinous space narrow, 

 lanceolate. 



The genus Brissus connects the genus Spatangus with 

 Amphidotus. It has the form of the latter with the 



