432 ECHINOMETRA MACROSTO.MA. 



porie genital is but slightly larger than the other genital plates, which are 

 uniform in size. The auricles are prominent, connected by a low interam- 

 bulacral arch, flattened, anchor-shaped, with a large auricular arch. Actinal 

 cuts well marked, somewhat rounded ; actinostome larger, in proportion to 

 the size of the test, than in any other species of the genus. The spines 

 arc proportionally short. 



Zanzibar; Red Sua; East India Inlands ; Japan; Sandwich Islands; Feejee Islands. 



Echinometra macrostoma 



Ellipsechinus macrostomus Ldtk., 1864, Bid. 

 Echinometra macrostoma A. A.G, 1872, Rev. Ech., Pi. I. |>. 116. 



The following i< Dr. Li'it ken's description of this species: — 

 General facies of an Echinometra. The shape is regularly oval; the 

 actinostome and the actinal cuts somewhat larger than is usually the case 

 in Echinometra. The ambulacra] lips three times as broad as the inter- 

 ambulacral lips; the Latter are evenly cut off. the former indented in the 

 middle. The auricles low hut .strong, scarce]} connected. The interamliu- 

 lacral tubercles in six clo-e vertical rows; the two primary ones not much 

 larger than the others near the ambitus, Imt are the only ones reaching the 



upper part of the test, the others being reduced to small granules; there 



are seventeen to eighteen tubercles in each vertical row. There are also 

 only two rows of principal tubercles near the mouth, the two middle rows 

 disappearing, and the two outside ones becoming very small to make room 

 for the petaloidal ambulacra. There are about twenty-four primary ambu- 

 lacra] tubercles in the principal vertical rows ; near the ambitus they are as 

 large as the secondary interamhulacral tubercles; in the upper part of the 

 test, however, considerably larger than the corresponding interamhulacral 

 ones. A secondary row of tubercles is wedged in between the primary 

 ambulacra] tubercles and the poriferous zone, but disappears on the lower 

 side, which is completely filled by the poriferous zone, the primary ambu- 

 lacral tubercles dwindling down to a very small size on the actinal Bide. 

 The average number of the pores in each arc is eight; this number de- 



