480 AMBLYPNEUSTES GRISEUS. 



Amblypneustes griseus 



! Echinus griseus Blaixv., 1825, Diet. Sc. Xat. O. 



! Amblypneustes griseus Agass., 1841, Monog. Scut. \_Pl. XXXYIII. f. 20, 21. 



Test comparatively stout, somewhat depressed, remarkable for its broad 

 poriferous zone and the size of the abactinal system. The tubercles in the 

 interambulacral space form one regular horizontal line in the centre of 

 each coronal plate ; the principal vertical row of primary tubercles is not as 

 marked as in A. ovum, the tubercles are more uniform in size, and extend- 

 ing to the median line, leave but a very narrow space covered by granules. 

 The sutural pores are more distinct, and the median ambulacra! space is 

 comparatively narrower than in A. ovum ; the broad poriferous zone is 

 frequently somewhat sunken. The secondaries and granules between the 

 pores in the poriferous zones are quite prominent, and form two more or 

 less regular vertical rows ; the tuberculation of the median space is close ; 

 the vertical arrangement distinct near the poriferous zone, but less marked 

 towards the median line. There are as many as seven tubercles in a hori- 

 zontal row in the interambulacra for each plate, and half the number in 

 the ambulacra] space. The color of the test varies from a greenish-yellow 

 to an ashy color; poriferous zone brighter colored. Ornamentation of the 

 median lines of both areas very indistinct; abactinal system with large anal 

 system. Spines comparatively stouter and less tapering than those of A. 

 ovum ; light green or violet, tipped with darker color or orange. 



Amblypneustes ovum 



! Echinus ovum Lamk, 1816, Ann. s. Vert. 



! Amblypneustes ovum Agass., 184G, C. R. Ann. Sc. Xat., VL 



Pi YllP.f. s,4. 



Test thin ; outline regularly ovoid ; sutural pores of median lines both 

 in the ambulacra! and interambulacral spaces wanting or rudimentary. In 

 the interambulacral space there is one primary vertical row of tubercles, with 

 smaller tubercles forming one to two irregular horizontal lines on the coronal 



