202 



indications of angles; length to breadth, .8:1.2. Arm-spines 

 rather stout, flattened, cut off square at the end, varying in length ; 

 about six in number on joints close to disc; two upper ones much 

 the stoutest and longest, and of about equal length, viz : 2.7 mil- 

 lim. ; sometimes, however, the upper one is very short and stout ; 

 three lowest spines minute and slender, the longest not longer 

 than .8 millim. ; a little further out on arm only five spines, two 

 large, one medium, and two small. The large spines have, on their 

 flat sides, diagonal rows of smooth, microscopic tubercles, which 

 give them a wavy, or corrugated appearance. One tentacle-scale, 

 represented by a microscopic thorn. Color, in alcohol : above, 

 disc uniform, light, Indian red ; arms dull purplish, with a very 

 distinct longitudinal line of black, bounded on each side by a clear 

 Avhite line ; spines glassy, with a pink hue ; below, mouth-appa- 

 ratus and under arm-plates white ; interbrachial spaces Indian 

 red without, but yellowish toward the mouth. 



Variations. The number of spines sometimes rises to nine, of 

 which five are large and four very small. The mouth-shields, 

 instead of being regularly oval, may have their lateral corners 

 quite sharp. 



This species may be readily distinguished from all others of 

 Florida, by the granulation of the disc, the character of the spines, 

 and the regular form of the upper arm-plates. 



Locality, east coast of Florida. Prof. Agassiz. 



Museum of Comparative Zoology, Cambridge. 



CORRECTIONS IN THE NOMENCLATURE OF OPHIURID^. 



No one has yet been able to identify Say's Ophiura appressa. 

 It is evidently a true Ophiura, ( Ophioderma, M. & T.) but the 

 question is, which species ? 0. serpens, guttata, hrevicauda, and 

 variegata disagree with Say's description, in having all the arm- 

 spines of equal length. 0. cinerea {Antillarum, Ltk.) has radial 

 shields, and has the upper arm-plates broken. 0. rubicunda dis- 

 agrees in having radial shields, and in color. 0. squamosissima 

 differs in its peculiar scaly arms.. Finally, 0. elaps disagrees in 

 the number and form of its spines. No species remains but 0. 

 virescens, described by Dr. Lutken, and this is doubtless the spe- 

 cies previously described by Say ; first, because the gray variety 

 agrees perfectly with Say's description ; second, because it is 



