228 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Glyptocidaris. 



A. Agassiz, 1863. Proc. Acad. Nat. Sci. Philadelphia, p. 356. 

 Type-species, Glyptocidaris crenularis A. Agassiz, 1. c. 



This, the only living genu.s of the family, is distinguished from all of its 

 extinct allies, by the structure of the ambulacra. Each plate is made up of five 

 elements, an adoral primary being followed by a demi-plate, a middle primary, 

 an upper demi-plate, and an aboral primary. Near the ambitus the pore-pairs 

 of the aboral primary, the upper demi-plate and the middle primary form an 

 oblique arc of three, which is followed by an arc of two made up of the pore-pairs 

 of the lower demi-plate and the adoral primary; this alternation is marked by 

 the fact that the outermost pore-pair of each plate is that of the middle element 

 while the pore-pair of the aboral primary is further in than that of the upper 

 demi-plate; that of the lower demi-plate is directly below that of the aboral 

 primary, while that of the adoral primary is further out. As we follow the 

 ambulacrum dorsally, we find the pore-pairs come to lie more and more in a 

 single vertical series and are never diplopodous as in Phymosoma and allied 

 genera. 



Glyptocidaris crenularis A. Ag. 



Glyptocidaris crenularis A. Agas.siz, 1863. Proc. Acad. Nat. Sci. Philadelphia, p. 356. 



Plates 90, figs. 5-10; 92, figs. 1-11; 106, figs. 1, 2. 



This species appears to be confined to the coasts of northern Japan. It was 

 first discovered near Hakodate by Stimpson and has been recorded from the 

 same region by Doderlein (1906, Zool. Anz., XXX, p. 520). It appears to be not 

 only local but rare, for the '"Albatross" took but few specimens. The largest 

 (PI. 106) measures 75 mm. in diameter and the primary spines arc about 50 mm. 

 long. 



These specimens were taken at the following stations: — 



Station 4807. Off Cape Tsiuka, Japan; 41° 36' 12" N., 140° 36' E. 44-47 

 fathoms. Sh., crs. g. 



Station 5046. Off Kinka San Light. Japan; 38^ 15' 7" N., 141° 44' 20" E. 

 Bott. temp. 50.8°. 82 fathoms. Dk. gy. s., p. 



Four specimens. 



