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CLARK: PUGET SOUND ECHINODERMS. 
? Arbacia stellata (Blainv.). 
There is a denuded test, 40 x 19 mm., pale brown in color, 
which is clearly an Arbacia and probably belongs to this species, 
though Puget Sound is somewhat north of its known range. 
Diadema mexicanum A. Ag. 
There is a single example of a Diadema in which all the spines 
are broken. It measures 65 mm. in diameter. Although Puget 
Sound is north of the known range of the species, there seems no 
doubt that the specimen is one of mexicanum. 
Strongylocentrotus purpuratus (Stimpson). 
There is a denuded test of this species, 51 mm. in diameter, and 
three other specimens, from 38 to 46 mm. These four specimens 
vary in color from light greenish to bright purple. The coronal 
plates are 16, 18, 18, and 19, respectively, from smallest to largest. 
The spines vary from 7 to 12 mm. in length. The pores are 8 or 9 
pairs in each zone at ambitus, where they are nearly horizontal; 
above ambitus there are 8 pairs, and they are more nearly vertical. 
There is also a small urchin, only 22 mm. in diameter and 12 
high, with spines 6-8 mm. long and only 13 coronal plates. The 
color is very pale. There are only 6 or 7 pairs of pores, and they 
are nearly vertical even at ambitus. It is possible this is a small 
specimen of S. franciscanus A. Ag., but it is probably a young 
purpuratus . 
Strongylocentrotus drobachiensis (Mull.). 
A single specimen (80.mm. in diameter) and fragments of two 
others of this cosmopolitan species are in the collection. The test is 
da7k purple, and the short spines (10-12 mm.) are light green. 
Echinometra oblonga (Blainv.). 
There is one very good specimen of this handsome species, which 
agrees perfectly with specimens in the National Museum. It is 
73 mm. long x 58 wide x 24 high. The spines are very numer. 
