COMMON SUN-STAR. 1 1 3 



rays are generally twelve or thirteen in number, sometimes 

 as many as fifteen. They are about one half as long as 

 the disk is broad. They are somewhat rounded, but the 

 disk is flat. The upper surface is covered by tubercles, 

 which are arranged in regular rows on the arms, but are 

 scattered on the disk. Each of these tubercles bears a 

 bundle of long spiculiform striated spines, eighteen or 

 twenty in each fasciculus. On the arms there are generally 

 five rows of these spiniferous tubercles. The intermediate 

 spaces are reticulated. The madreporiform tubercle is 

 sublateral, and striated in a radiating manner. Beneath, 

 the avenues are lanceolate. Their immediate border con- 

 sists of longitudinal fasciculi of spines, four or five in each 

 fasciculus. Next to these are regular transverse rows of 

 spines placed on transverse ridges, eight or ten in each 

 row. The third series forms a bordering to the arms, and 

 consists of sets of from eighteen to twenty long fasciculated 

 spines placed on broad compressed articulated bases. The 

 mouth is protected by a beautiful and peculiar mechanism. 

 The angles formed by the joined origins of the rays each 

 bear an ovate sub-triangular plate, grooved down the 

 centre, and carrying two semicircles of long tapering spines, 

 which project in a comb-like manner over the mouth. A 

 similar organization is seen in the purple Sun-star. 



In the genus Solaster the eyelid is not composed of a 

 circle of spines, as in most of the allied genera ; but of a 

 transverse terminal row, which laps like the fingers of a 

 hand over the eye. In Solaster papposa these spines are 

 separate, and much longer than those around them ; but 

 in Solaster endeca they are united together, or webbed, so 

 as to form an almost solid piece, which is bilobed. This 

 eyelid forms a very perfect protection to the eye, and if 

 closed, it is extremely difficult to force it open against the 



