AGASSIZ AND CLARK : REPORT ON ECHINI. 139 



while the posterior petals are 2 mm. long and have only 7 pairs of pores. The 

 labial plate is short and in contact with only one ambulacral plate on each side, 

 and the actinostomal membrane carries only very small plates, while in rotundus 

 the labial plate is long and in broad contact with two ambulacral plates on each 

 side, and the actinostome is covered by four large and six or seven smaller plates. 

 We are forced, therefore, to regard this specimen as a young example of an un- 

 described species. The test and spines are nearly white, while the peripetalous 

 fasciole is purple. 



Station 4913. Southwest of Koshika Islands, Japan, 391 fathoms. 



One specimen. 



