336 HAWAIIAN AND OTHER PACIFIC ECHINI. 



GONIOPNEUSTES. 



Duncan, 1889. Journ. Linn. Soc. London. Zool., XXIII, p. 113. 

 Type-species, Amblypnfiistes pentagonus A. Agassiz, 1872. Bull. M. C. Z., Ill, p. 56. 



There can be no doubt that Duncan was quite right in instituting a new 

 genus for the remarkable and apparently very rare sea-urchin, which A. Agassiz 

 described in 1872 as an Amblypneustes from Mauritius. The abactinal system 

 with oculars I and V fully insert, the high coronal plates, the presence of scattered 

 plates on the buccal membrane, the scarcity of spines and the large size of the 

 primaries combine to make the genus unusually well characterized. The type 

 and only known species was based on a single specimen, in the M. C. Z. collec- 

 tion, and figured in the Revision. (Since the text states correctly the measure- 

 ments of the specimen as 22 X 21.5 mm. while the figures on PL VIII C measure 

 32 X 30 mm., it is evident that the "explanation of the plate" is erroneous in 

 saying the figures are natural size.) The locality, whence this specimen came, 

 is very doubtful. It was purchased in Hamburg in 1870 and bears the label 

 "Brandt. Hamburg." It is entered in the M. C. Z. catalogue as from "lie de 

 France?" So far as known, no other specimens are to be found in museums, 

 and neither Pike nor Mobius, nor Robillard in their extensive collecting at 

 Mauritius ever met with this remarkable echinoid. It is most probable that the 

 specimen came from Australia. 



Goniopneustes pentagonus Duncan. 



Amblypneustes pentagonus A. Agassiz, 1872. Bull. M. C. Z., Ill, p. 56. 



Goniopneustes pentagonus Duncan, 1889. Journ. Linn. Soc. London. Zool., XXIII, p. 113. 



Plate 93, figs. 18-21. 



In addition to the characters given in the "Revision," the following points 

 may be mentioned. There are 18 interambulacral plates in each column and 

 each one bears a single, conspicuous, imperforate, non-crenulated tubercle. 

 There are also on each plate a few (6 in the mid-zone) well-spaced secondaries, 

 and some very minute and widely scattered miliaries; the latter bear pedicellaria? 

 but not spines. There are 43 ambulacral plates in each column but not more 

 than 12-15 carry primary tubercles; at the ambitus and below, every other 

 plate has a primary but above the ambitus, there are very few indeed. There 



