TRIPYLUS EXCAVATUS. 23 



are deeply concave. The separation, therefore, of Schizaster and allied gen- 

 era as a separate family from the Brissina, as has frequently been proposed, 

 on account of the structure of the sunken petals, is not warranted, as this 

 feature is evidently of very secondary importance. So that it seems even 

 doubtful whether the genus Tripylus, as I have hinted in the Revision of 

 the Echini, should be distinguished from Schizaster proper, and whether 

 Schizaster, Trij^ylus, Hemiaster, Brissopsis, should not be considered as sub- 

 genera of one genus. At any rate, the relationship of such apparently widely 

 separated forms as Schizaster, Linthia, Tripylus, Hemiaster, Faorina, and 

 Rhynobrissus is very close. 



Lat. 37° 42', South; Long. 5G° 20', West. 



