2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. G9 



3. Foi'iuu (wunthostomd (Verrill). Intergrades with alveolata; 

 typical specimens ditfer in liavintr nniforml}' small abactinal spines 

 which stand in sin<>le file on the irregular reticulum of the skeleton 

 and divide the abactinal area into areolae ; or are more grouped and 

 scattered so that the reticulation is not so evident; superomarginal 

 spines in combs or groups of three to five (single, or irregularly one 

 and two in alveolata) . Evasterias acanthostoiiva Verrill. (Unalaska 

 to Puget Sound.) 



EVASTERIAS ECHINOSOMA, new species 



Diagnosis. — Size, large; rays five, long, tapering, stout, more or 

 less swollen, with a very convex abactinal, and a subplane actinal 

 surface. Differing from E. troscheUi in having imiformly large, 

 mostly subcorneal, well-spaced abactinal spines; marginal plates un- 

 usually high on side of ray, the superomarginals being abactinal in 

 position and generally monacanthid; six (or five) series of actinal 

 plates (generally monacanthid) of which either the upper row or 

 the inferomarginals define the margin of the ray ; adambulacral 

 plates triplacanthid, or displacanthid and triplacanthid. Type: 

 R— 330 mm., v=.bl mm., R=6.4 r; brr^about GO mm. 



Descnption. — The abactinal surface is armed with rather widely 

 spaced and nearly uniform robust spines, cylindrical at the base, 

 the distal half conical, longitudinally sulcated, bluntly pointed, and 

 in giant specimens with E 300 mm., about 2.5 mm. long by 1 to 1,5 

 mm. thick at the base. The distal part of the spine may^ be slightly 

 swollen so as to appear subcapitate. The spines of the distal portion 

 of the ray are round tipped, and by a shortening and rounding of 

 the terminal conical portion a subglobose, striated tip results. A 

 majority of spines are so formed in specimens from stations 3281 

 (2), 3291 (1), 3235 (1), none of which have R greater than 200 mm. 

 In the specimen from station 2842 the spines are slenderer than in 

 the type, tapering and pointed. The spines do not have a regular 

 arrangement. An irregular carinal series is generally fairly well 

 marked, the dorsolaterals standing typically singly (but sometimes 

 in groups or lines of 2, 3, or even 4) on the chief nodes of the 

 reticular skeleton. In some of the very large specimens there are 

 a few very delicate terete spinelets, scarcely larger than the abac- 

 tinal straight pe'dicellariae, scattered over the abactinal surface. 

 In the specimens on which the spinelets are more or less grouped 

 there is rather less uniformity in size, some being of distinctly sec- 

 ondary size. There is a broad and pretty definite supramarginal 

 channel bounded abactinally by a very irregular row of dorsal 

 spines wdiich usually but not always stand closer together than on the 

 rest of the dorsolateral region. 



