POROCIDARIS VARIABILIS. 30 



The general aspect of P. variahiJis (PL 17) is much like that of P. Sltarrcri 

 (PI. 3, " Blake " Echini, Mem. M. C. Z., X, No. 1). It diifers from P. Sharreri 

 in having the genital plates united as in P. Cohosi (Panamic Deep Sea Echini, 

 PI. 11, figs. 5, 6), while they are separated by the anal plates in P. Sharreri 

 (PL 4, fig. 2 "Blake " Echini). In the latter the secondary tubercles round 

 the scrobicular circle are larger and the secondaries and miliaries are arranged 

 in rows parallel to the horizontal suture of the median interambulacral zone 

 (PL 4, fig. 1 "Blake " Echini), while they are of more uniform size and more 

 irregularly arranged in P. variabilis (PL 19). 



The general aspect of the smaller specimens of P. variabilis (PL 22) is 

 more like that of P. elegans ("Challenger" Echini, PL 3, fig. 1). It is 

 difficult to determine to just how great an extent variabilis differs from 

 Yoshiwara's P. misakiensis, but if we may rely on de Meijere's^ figures oi 

 the latter, variabilis has a much smaller abactinal system, and smoother and 

 more slender primaries. 



Although this species resembles Cuhosi in the entire absence of globiferous 

 pedicellariae, the tridentate show some peculiarities. They are very vari- 

 able (PL 8, figs. 1-11), occasionally having only two valves, sometimes four. 

 The valves are broader and less tapering than in Cobosi, and the tip is 

 rounded or little pointed. They vary in length from .50 up to 4.00 mm. 

 and the stalk is always shorter, sometimes only half as long. The Lirgest 

 occur actinally as well as above the ambitus, but are often present in 

 numbers on the abactinal system. 



Specimens of JPorocidaris variabilis were collected at the following stations : 



Station 3865. Off Mokuhooniki Islet, Pailolo Channel. Bott. temp. 

 44.8-45°. 256-283 fathoms. Fne. vol. s. r. 



Station 3866. Off Mokuhooniki Islet, Pailolo Channel. Bott. temp. 

 43.8°. 283-284 fathoms. Gy. m. fne. s. 



Station 3883. Off Mokuhooniki Islet, Pailolo Channel. Bott. temp. 

 45.2°. 277-284 fathoms. Glob. oz. 



Station 3893. Off Lae-o Ka Laau Light, Kaiwi Channel. Bott. temp. 

 47°. 220-346 fathoms. Fne. wh. s. r. 



Station 3918. Off Diamond Head, Oahu. Bott. temp. 44. 5\ 257-294 

 fathoms. Wh. s. m. 



Station 4081. Off Punlawa Point, Maui. Bott. temp. 51.7°. 202-220 



fathoms. Gy. s. for. 



1 Die Echinoidea der Siboga-Expedition, 1904. PI. II, figs. 15, 16. 



