238 HAWAIIAN AND OTHER PACIFIC ECHINI. 



These are trivial differences, but taken together they warrant keeping the species 

 apart. The geographical isolation of the Hawaiian species is notable, but it 

 seems more nearly related to the Japanese species, liitkeni, than to the geographi- 

 cally nearer calif ornicus. 



Station 3863. Off Mokuhooniki Islet, Pailolo Channel, Hawaiian Islands. 

 Bott. temp. 60°-61°. 127-154 fms. Brk. co., crs. gr., r. 



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

 44.8°-45°. 256-283 fms. Fne. vol. s., r. 



Station 4096. Off Mokuhooniki Islet, Pailolo Channel, H. I. Bott. temp. 

 45.3°. 272-286 fms. Fne. gy. s. 



Station 4097. Off Mokuhooniki Islet, Pailolo Channel, H. I. Bott. temp. 

 44.2°. 286 fms. Fne. gy. s. 



Station 4116. Off Kahuku Point, Oahu, H. I. Bott. temp. 48.8°. 241- 

 282 fms. Co. s., for. 



Bathymetrical range, 127-286 fms. Extremes of temperature, 61°-44.2°. 



Twelve specimens, mostly crushed. 



Spatangus inermis. 



Mortensen, 1913. Mitt. Zool. Stat. Neapel, 21, p. 24. 



This recently recognized Mediterranean species is known as yet only from 

 the Gulf of Naples, where it occurs at depths of 14-45 fms. on sandy and muddy 

 bottoms. 



Spatangus liitkeni. 



A. Agassiz, 1872. Bull. M. C. Z., 3, p. 57. 



Plates 146, fig. 17; 157, figs. 5, 6. 



For purposes of comparison with nearly related forms, it has seemed desir- 

 able to give some figures of this species. The side and rear views (PI. 157, figs. 

 5, 6) of a small specimen are shown for comparison with similar views of the 

 following species. Attention may be called to the short vertical diameter, 

 the flatness of the sternum, and the slight prominence of the Bubanal plastron. 



Pedicellariae are abundant but are nearly all trident ate. A few triphyl- 

 lous, with valves about .12 mm. long, were found, but no globiferous, ophicepha- 

 lous, or rostrate were seen. The Blender tridentate show a remarkable diversity 



