202 DESCRIPTION OF THE PLATES. 



Plate XIV. 



Fig. 1. Echinus microstoma (p. 149), nat. size, to show the general 



aspect of the species with the spines on. 

 Fig. 2. Part of test of same, x 2, to show the characters of the 



ornamentation of the test. 

 Fig. 3. Echinus elegans (small specimen) (p. 154), nat. size, to show 



the general aspect of the species with the spines on. 

 Fig. 4. Part of test of same, x 2, to show the same points as fig. 2. 



Plate XV. 



Fig. 1. Strongylocentrotus droebachiensis (p. 156) ; portion of test, 

 x 2, to show the arrangement of the tubercles on the 

 amhulacral and interambulacral plates, and some of the 

 variations exhibited by the number of pores in an arc. 



Fig. 2. Spho?rechinus granulans (p. 158) ; portion of test, X 2, to 

 show the arrangement of the tubercles and of the pori- 

 ferous plates. 



Fig. 3. Spharechinus granulans, to show the ordinary appearance 

 of the species, nat. size. 



Plate XVI. 



Fig. 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. 

 Figs. 2- 4. Outlines of tests of the same, nat. size, to show some of 



the variations exhibited in the shape of the test. 

 Fig. 5. EcMnocardium 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. 

 Fig. 6. Echinocardium flavescens (p. 171), nat. size, from above ; 



the absence of an anterior groove is to be noted. 

 Fig. 7. The same, seen from below. 



Fig. 8. Echinocyamus pusittus (p. 160), x 2, seen from above. 

 Fig. 9. The same, x 2, seen from below. 

 Fig. 10. Outline of labrum of Spatangus purpureus (p. 165), nat. 



size, to be compared with 

 Fig. 11, in which the more pointed labrum of Spatangus raschi 



(p. 167) is shown. 



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