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DESCRIPTION OF THE PLATES. 
Prats XIV. 
Echinus microstoma (p. 149), nat. size, to show the general 
aspect of the species with the spines on. 
. Part of test of same, x2, to show the characters of the 
ornamentation of the test. 
. Echinus elegans (small specimen) (p. 154), nat. size, to show 
the general aspect of the species with the spines on. 
. Part of test of same, x 2, to show the same points as fig. 2. 
Prats XV. 
. Strongylocentrotus droebachiensis (p. 156); portion of test, 
x 2, to show the arrangement of the tubercles on the 
ambulacral and interambulacral plates, and some of the 
variations exhibited by the number of pores in an arc. 
. Spherechinus granularis (p. 158); portion of test, x 2, to 
show the arrangement of the tubercles and of the pori- 
ferous plates. 
. Spherechinus granularis, to show the ordinary appearance 
of the species, nat. size. 
Prate XVI. 
1. Echinocardium cordatum (p. 169), nat. size, to show the 
general appearance of this common species when found, as 
it often is in abundance, thrown up on the sea-shore. 
The disposition of the pores is to be specially noted. 
2-4, Outlines of tests of the same, nat. size, to show some of 
the variations exhibited in the shape of the test. 
5. Echinocardium pennatifidum (p. 170), nat. size ; the spines 
remaining on the left side, but removed from the right, so 
as to show the disposition of the pores. 
6. Echinocardium flavescens (p. 171), nat. size, from above ; 
the absence of an anterior groove is to be noted. 
. The same, seen from below. 
. Echinocyamus pusillus (p. 160), x 2, seen from above. 
a 
8 
9. The same, x 2, seen from below. 
0 
. Outline of labrum of Spatangus purpureus (p. 165), nat. 
size, to be compared with 
. 11, in which the more pointed labrum of Spatangus raschi 
(p. 167) is shown. 
PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. 
