316 ECHINARACHNIUS PARMA. 



Echinarachnius parma 



! Scutella parma 1. S.M. 1816. An. ?. Vert. 

 ! Echinarachnius parma Gray, 1825. An. Phil. 



PI. XI". f. 4, 5 ; PL XP. f. 4, .: ; PL XII. f. 1-13. 



As the measurements of the accompanying specimens of this species show, 

 the variations in the outline, both from above and in profile, as well as the 

 shape of the petals, are considerable. The outline from above may lie either 

 nearly circular or somewhat pointed anteriorly, or decidedly truncated pos- 

 teriorly, with deep indentations for the amis and in the median ambulacra! 

 spaces. The profile may he regularly sloping from a nearly central apical 

 system, with a thin edge of test, or we may have a thick edge of test, and an 

 arching central part of the test from the outer edge of the petals. The posi- 

 tion of the apex is also sometimes somewhat eccentric posteriorly, showing 

 that this character alone cannot he of generic value, as had been taken for 

 granted in Dendraster. The apical system is well marked, hut differs con- 

 siderably in specimens of the same size; the rosette is generally open at the 

 extremity in Hat specimens, while in more arched ones the petals have a 

 decided tendency to converge at the outer end ; the poriferous /.one is nar- 

 row, not more than from one quarter to one fifth the width of the ambulacra. 

 The marginal ramifications of the ambulacra! furrows arc frequently quite 

 indistinct in older specimens. The tubercles are closely surrounded by 

 miliaries, covering the whole upper part of the test, including the apical 

 system, with a line homogeneous granulation. On the lower surface near 

 the actinostome the tubercles are distant; they become, however, closely 

 packed at the commencement of the ramifications of the ambulacra! fur- 

 rows, although there is no miliary granulation on the lower surface so 

 characteristic of the upper part of the test. The spines of the lower sur- 

 face are larger, longer, and of variable length, those covering the opening 

 of the actinostome are the largest, while the spines of the upper surface are 

 shorter, and of uniform size. The color when alive is a beautiful crimson- 

 carmine, tending to greenish, or of intermediate shades; lower surface of 

 the same color ; ambulacra! furrows darker. 



The range of this species is quite astonishing, and its association on the 

 Asiatic coast with a second well-marked species has undoubtedly caused a 

 great deal of confusion, in addition to the presence of Arachnoides. which, 

 when covered by spines, might readily pass as either of the species of true 

 Echinarachnius. I am unable, upon examination of the originals, to dis- 



