56 BULLETIN OF THE 



plates moderately closely packed. The spines are short ; in dried speci- 

 mens, violet at base tipped with green, test violet with greenish tubercles. 

 Ecole des Mines; Mus. Comp. Zool. — Australia. 



Amblypneustes pentagonus. 



Unlike the other species of Amblypneustes, the outline of the test 



from above is pentagonal ; the ambulacra projecting considerably beyond 



the. concave interambulacra. The coronal plates are high, not half as 



numerous as in other species of the genus of the same size. There is 



but a single primary vertical row of tubercles both in the ambulacral 



and in the interambulacral spaces ; secondary tubercles few in number, 



very irregularly scattered ; sutural pores small, limited to angle of 



plates; test thin, high, remarkable for the great size of the primary 



spines. Abactinal system delicate, and not prominent and stout as in 



other allied species. 



Mauritius ? 



Amblypneustes inflatus.* 



Test moderately stout, nearly spherical ; poriferous zone more than 

 equalling in width the median ambulacral region, where the tubercles 

 form irregular horizontal rows of from two to three tubercles for each 

 plate. In the interambulacral space there is for each plate a larger 

 primary, forming a distinct vertical row, and from one to six smaller 

 tubercles on each side of the median interambulacral line forming 

 horizontal rows, and very indistinct vertical rows. No bare median 

 ambulacral or interambulacral spaces. 



New Holland. 



This as well as the following species belong to the section of Ambly- 

 pneustes (Holopneustes),t in which the poriferous zones are arranged 

 in three vertical rows of pores, the middle row often extremely sporadic, 

 as in H. porosissimus, and having no sutural pores. 



Amblypneustes purpurascens.* 

 Actinal and abactinal diameter equal, poriferous zone equal in width 

 to the corresponding tuberculiferous ambulacral space. In large speci- 



* Liitl-cn MS. in lift. 



t It is possible that these two species may turn out to be only different stages of 

 growth of II. porosissimus. The variation in the other species of Amblypneustes 

 is very great, but here is confined to the poriferous zone, which makes it difficult to 

 decide the point for want of material. 



