372 HAWAIIAN AND OTHER PACIFIC ECHINI. 



length; primary tubercles correspondingly big, especially noticeable abacti- 



nally; height of test usually .55-.60 of its length oblonga. 



Pore-pairs in arcs of 5, not rarely 6. 



Primary spines deep purplish or reddish; abactinal system with numer- 

 ous secondary and miliary spines, many of which are low, thick 



and truncate, or capitate; ambulacra petaloid actinally insularis. 



Primary spines light brownish, more or less extensively green distally, 

 usually purple-tipped; abactinal system remarkably free from spines; 



ambulacra not petaloid actinally viridis. 



Pore-pairs, at or above ambitus usually 7 or 8 in each arc, rarely only 6. 



Auricles stout with conspicuous supplementary "tags," arising vertically from 

 their united ends; few, sometimes none, of the arcs of pores with more than 

 6 pairs; test usually more than half as high as long with the width usually 

 about .85 of the length; primary spines usually much shorter than width 

 of test; valves of trident ate pedicellariac narrow at tip, in contact for most 



of their length lucunter. 



Auricles slender without conspicuous "tags"; pore-pairs usually 7 or 8; test 

 about half as high as long or less; width generally .90-. 95 of length; primary 

 spines nearly equal to short diameter of test; valves of tridentate pedicellaria; 

 widened at tip and in contact only distally Van Brunti. 



Echinometra Mathaei Bl. 



Echinus Mathai de Blainville, 1825. Diet. Sci. Nat., XXXVII, p. 94. 

 Echinometra Mathsei de Blainville, 1830. Diet. Sci. Nat., LX, p. 206. 



The specimens of this very common and wide spread sea-urchin, which 

 the "Albatross" collected from various parts of the Pacific, reveal the usual 

 diversities of color and form. Some of them are very fine examples of 

 the typical form, except that there are none in which the color is at all green. 

 The finest specimens are from Laysan and Manga Reva. The former have the 

 test dark brown, with the spines light pinkish fawn-color; the largest is 64 mm. 

 long, 53 wide and 40 high. Those from Manga Reva are not so large but are 

 much more handsomely colored as the spines are light purplish gray abruptly 

 tipped with cream-color. 



The following are the places, whence specimens were collected : 

 Station 3959. Near Laysan Island, Hawaiian Islands, 10 fathoms. Wh., s., co. 

 Laysan Island, H. I. Bora-bora, Society Islands. 



Necker Island, H. I. Fakarava, Paumotu Islands. 



Kamalina Bay, Niihau, H. I. Makemo, Paumotu Islands. 



Honolulu Reef, Oahu, H. I. Rangiroa, Paumotu Islands. 



Waikiki Beach, Oahu, H. I. Manga Reva, Paumotu Islands. 



Hilo, Hawaii, H. I. 

 Forty-nine specimens. 



