ECHINOMETRA VAN BRUNTI. 375 



abactinal system is about .20 of the length. The largest specimen is 45 mm. 

 long, without including the spines, which are long and slender as in Fan Brunti, 

 and may exceed the short diameter of the test. There are 10-14 primary inter- 

 ambulacral plates in each column. The pore-pairs are generally in arcs of five 

 at the ambitus but some of the abactinal arcs usually have six and in one or two 

 specimens most of the abactinal arcs have six. The ocular plates are all broadly 

 excluded from the periproct in the ten normal specimens examined. The small 

 spines abactinally, particularly on the abactinal system, are distinctly capitate 

 and many of them are remarkably low and stout (PI. 95, fig. 13). Actinally 

 the ambulacra become somewhat widened but they are not quite so distinctly 

 petaloid as in Van Brunti. The tridentate pedicellarise have rather narrow 

 valves (PI. 95, fig. 15) as in most Echinometras and they are not widened at the 

 tip as in Van Brunti. The pedicellarise of all kinds are rather rare and small; 

 the valves of the globiferous (PL 95, fig. H) are about .30 mm. or less, while 

 those of the tridentate and ophicephalous are only .30-.40 mm. No spicules 

 whatever were found in the tube-feet. The color of all the specimens is uniformly 

 deep purple or brownish red. 



Not having seen this species previously, it was supposed to be peculiar to 

 Easter Island, and it was therefore rather surprising to find that the Echino- 

 metras which the "Albatross" collected in March, 1889, at Socorro Island, must 

 be referred to the same form. One would naturally have expected Mexican 

 species in the Revilla Gigedo Islands, and it is therefore interesting to find no 

 specimens of Van Brunti, but instead oblonga at Clarion Island and insularis at 

 Socorro. 



The material consists of the following lots: 



Socorro, Revilla Gigedo Islands, Mexico, March, 1889. 



Easter Island, southeastern Pacific Ocean, Dec. 1904. 



Twenty-eight specimens. 



Echinometra Van Brunti A. Ag. 



Echinometra Van Brunti A. Agassiz, 1863. Bull. M. C. Z., I, p. 21. 



There are three fine specimens of this species before us, taken by the "Alba- 

 tross" in May, 1888. One of them is the largest example of this species seen, 

 measuring 73 mm. in length by 70 mm. in width, regardless of the spines, some 

 of which are 40 mm. long. 



Santa Margarita Island, Lower California, Mexico. 



Three specimens. 



