Verrill, Notes on Radiata. 443 



one side. The lai'ger spindles are usually somewhat oblong, blunt at 

 both ends, often irregular, closely covered with larger, very rough 

 warts, except on the inside, which bears rather large, prominent, sharp 

 spinules. The clubs are very stout and rough, often one-sided or irreg- 

 ular, the small end not very acute, covered with crowded rough warts, 

 the larger end much dilated, lacerately divided into many long, sharp, 

 often very slender, unequal spinules. The irregular spicula are very 

 short and thick, often nearly as broad as long, sometimes oval, very 

 rough with large, crowded, prominent, lacerate warts, one side lace- 

 rately divided into long, very sharp spinules. Very rough warty 

 heads occasionally occur, similar to the last. The small spindles are 

 mostly rather stout, blunt at the ends, and covered with very promi- 

 nent, not crowded, somewhat rough warts. The polyp-spindles are 

 mostly slender, acute, yellowish brown spindles, covered with small 

 but prominent warts. 



The larger sinndles measure -625""" by -225"°^ -600 by -200, -hlb by 

 •275, -575 by -200, -550 by -300, -550 by '250, '550 by -200, -550 ])y -175, 

 •500 by -225, -500 by 'l.^iO, ^475 by -200, ^450 by -200, '425 by -175, 

 •425 by •ISO, -400 by •ISO, -375 by •ISO, '350 by -175 ; the stout clubs 

 •575 by -300, -SSO by '300, '525 by •250, •SOO by ^250, •SOO by -200, "475 

 by -250, -475 by ^200, ^450 by ^225, -450 by ^200, ^425 by -225, ^425 by 

 •200, ^425 by -175, ^400 by -225, -400 by ^200, -400 by •175, '325 by 

 •200, ^325 by ^150 ; the irregular stout spicula "575 by -325, '575 by 

 •250, -550 by ^275, "525 by "300, ^500 by '250, '450 by ^175, ^400 by ^300, 

 •400 by ^200, '375 by -225, -350 by '175, -325 by ^225, ^325 by ^200 ; 

 the heads "325 by ^225, ^300 by ^275 ; the small spindles -300 by •112, 

 •262 by -100, ^250 by ^125, -250 by -100, '225 by -112, ^200 by •lOO; 

 the polyp-spindles ^262 by '037, ^250 by -050, ^225 by '062, ^225 by 

 •050, •I 75 by •OSO. 



Pearl Islands and Panama, in rocky pools at low-water mark, com- 

 mon, — F. H. Bradley ; Panama, — J. H. Sternbergh, A. Agassiz ; Aca- 

 pulco, — A. Agassiz ; Corinto, — J. A. McNiel. 



This species diiFers from most others in color and in the small gran- 

 ulous verrucae. M. retusa, which has a somewhat similar but darker 

 color, has much larger, spreading verrucae and very different larger 

 spicula. In some respects it is allied to M. hebes, which it considera- 

 bly i-esembles, except in color, when young. Young specimens of 

 these two species were formerly confounded by me, — a mistake that 

 might readily have been avoided by an examination of the spicula, 

 which are very different. The spicula of this species are remarkable 

 for their relatively small size, roughness, and stout forms, among which 

 the thorny clubs are, perhaps, the most characteristic. 



