194 THE ATLANTIC. [chap. iv. 



cies extend as far to the northward as the East Indies and 

 Natal. 



Fig. 41.— Goniocidar is canaliculata, A. Agassiz. Stanley Harbor. Twice the uatnral size. 



This sj)ecies (Fig. 41) has a general resemblance, at a first 

 glance, to the small Mediterranean variety {affinis) of Cidaris 

 pcvpiUata, but the radicles are thinner and much shorter, and 

 differ wholly in their sculpture ; the shell is even more de- 

 pressed ; the secondary tubercles are more distant ; and a very 

 regular series of short club-sliaped rays seated on miliary gran- 

 ules are interposed in the rows between the spines of the sec- 

 ond order. The ovarial openings are extremely minute, and are 

 placed close to the outer edge of the ovarial plates. The upper 

 part of the test is quite flat, the flat space including not only 

 the ovarial plates and the plates of the periproct, but the first 

 pair, at least, of the plates of each inter-ambulacral area. Artic- 

 ulated to the primary tubercles of these latter are two circles 

 of radioles, the inner more slender and shorter, the outer stout- 

 er and longer, but both series much larger than radioles usually 

 are in that position on the test. 



