6J: MACEOPJSfEUSTES SPATAKGOIDES. 
* Macropneustes spatangoides A. Ag. 
Spatangus purpureus A. Ag. (iion Leske nee auct.). Bull. M. C. Z., VIII., No. 2, p. 83, 1880. 
Lesser Antilles. 82-373 fathoms. 
PI. XXVII. 
The fragments of the Spatangoid which I referred in the Preliminary Re- 
port to Spatangus purpureus, I find on closer examination to belong to the 
genus Maci-opneustes. Although no complete living specimen was dredged, 
yet a sufficient number of dead broken tests were collected to enable me to 
restore this species satisfactorily, with the exception of the part near the 
anal system. In general appearance and outline, as seen from above, this 
species resen\b\es Spaiaiiffus purpureus ; but it can at once be distinguished 
by the high anterior part of the test, which in the abactinal part of the odd 
ambulacrum rises above the apical system. 
The anterior ambulacrum is deeply sunken at the ambitus, in a groove 
similar to that of Liiiopncustes loiujispiims. In old specimens the abactinal 
part of the ambulacral petals are disconnected, much as in Echinocardium, 
within the internal fasciole. On the actinal surface the tuberculation is quite 
uniform in specimens of very different size.s. The larger primary tubercles 
are found on the anterior part of the test, and in the posterior interambula- 
cral area they diminish gradually in size towards the posterior extremity^ 
and become more closelj'' crowded. The tubercles of the actinal plastron 
are smaller and of uniform size. On the abactinal surface the primary 
tubercles are limited to the interambulacral areas within the peripetalous 
fasciole, except along the line of the middle of the posterior interambu- 
lacral area, along which the V-shaped angular lines of primary and sec- 
ondary tubercles extend, gi-adually diminishing in size towards the anal 
system. Within the peripetalous fasciole the arrangement of the primaries 
varies greatly. In some specimens there are not more than nine or ten 
large tubercles in the apical part of the interambulacral areas; in others 
the primary tubercles form V-shaped figures in each plate, the smaller tuber- 
cles on the lower side of the plates. In other specimens, again, the large 
tubercles form merely irregular horizontal lines. The rest of the surface 
of the test within the petaloid area to the actinal side is closely packed with 
small miliary tubercles, often concentrated more or less on the lower part 
of the coronal plates so as to form V-shaped areas. The petaloid ambulacra 
