AGASSIZ AND CLARK: REPORT ON ECHINI. 241 



Nccker Island. 



Lanai Island. 



Puako Bay, Hawaii. 



Kamalino Bay, Niihau. 



Napeli, Maui. 



One hundred and three specimens. 



Echinometra Mathaei Bl. 

 Echinus Mathaei de Blainville, 1825. Diet. Sci. Nat, 37, p. 94. 

 Echinometra Mathaei de Blainville, 1834. Man. d'Actin., p. 225. 

 The series of Echinometras is quite easily divisible into two sets, one of which 

 consists of individuals with high, usually elongated tests, large tubercles, stout 

 spines and relatively small (.17-23 of long diameter) abactinal system. These 

 are evidently the wide-ranging and common Mathaei (formerly called lucunler). 

 Honolulu reefs. 

 Kamalino Bay, Niihau. 

 Laysan Island. 



Station 3959. Off Laysan Island, 10 fathoms. 

 Thirteen specimens. 



Echinometra picta A. Ag. and Clark. 



The other set of Echinometras has the test much natter, the height rarely over 

 .50 of the long diameter, the abactinal system larger (.24-30 of the long diam- 

 eter), the tubercles smaller, giving the abactinal surface a much more bare ap- 

 pearance than in Mathaei, and the spines longer and more slender. These two 

 forms are not sharply set off from each other, but there are few individuals which 

 cannot be distinguished at a glance, and it seems desirable to give the flat indi- 

 viduals a name. Similar specimens are in the Museum collection from the Society 

 Islands, but not from the East Indies, or west thereof. This species seems to 

 bear the same relation to Mathaei that viridis of the West Indies does to lucunter 

 (formerly called subangularis}. 



Honolulu reefs. 



Puako Bay, Hawaii. 



Necker Island. 



Kamalino Bay, Niihau. 



Napeli, Maui. 



Station 3975. Off Necker Island Shoal, 16-171 fathoms. 



Twenty-nine specimens. 



Echinometra oblonga Bl. 



Echinus oblongus de Blainville, 1825. Diet. Sci. Nat., 37, p. 95. 

 Echinometra oblonga de Blainville, 1834. Man. d'Actin., p. 225. 



A good series of this species was taken, none of which show the least approach 

 to mathaei or afford the slightest difficulty in identification, without reference to 

 the spicules in the pedicels ! (vide de Meijere, 1904, and Doderlein, 1906). 

 vol. l. — no. 8 16 



