Verrill, JVotes on Radiata. 271 



Order, ASTERIOIDEA. 

 Luidia tessellata Lutkeu. 



Luidia tessellala Liitkeu Yidonsk. Meddelelser, 1 859, Bidrag til Kundskabom de ved 

 Kysterne af Mellcm- og S3-d-Aiiierika levende Alter af Sostjerner. p. IG. 



ScA-eral specimens of tliis species, of various sizes, were obtained by 

 Mr. Bradley at Panama, and one small one at Acajutla. Dr. Liitken's 

 specimens came from Puntarenas and Realejo. 



Our lari^est specimen measures, from the center of disk to tip of 

 rays, 6 '5 inches ; to border of disk 1 inch; width of rays at base, not 

 including spines, l-I, A medium sized specimen measures 3*4 inches 

 from center to end of rays ; and -6 to edge of disk ; rays -V wide at base. 



The rays are depressed and taper regularly to the ends, which are 

 more slender in the small than in the large specimens. The interam- 

 bulacral* plates bear a slender, sharp, and strongly curved spine on 

 the inner edge, and more externally a group of three or four longer 

 and stouter ones^ of which the inner stands singly, the two next side 

 by side, and the outer, when present, singly. The ventral plntes are 

 covered with numerous unequal, minute, sharp spines and bear a cen- 

 tral row of eight to ten small, stout spines, and usually three long, 

 sharp, marginal ones, which are somewhat curved in the direction of 

 the ends of the rays, and longer than the interambulacral spines 

 (•3 of an inch in large specimens). The upper surface is crowdedly 

 covered with elongated paxillne, which are much larger along the 

 sides of the rays than in the middle and upon the disk, where they 

 become very small and close. Those of three marginal rows on each 

 side are considerably largest and somewhat quadrangular, bearing at 

 the top a central group of six to ten small, short, blunt, or rounded 

 tubercles, surrounded by numerous, fine, slender, diverging papillse. 

 Toward the center of the rays and on the disk, they usually bear only 

 one or two small, rounded tubercles, surrounded by similar papillae. 



The color of a dried specimen is yellowish green above and yellow 

 beneath ; in alcohol, brownish green above, yellowish beneath. 



This species is allied to L. clathrata of Florida and the Carolina 

 coast, but has broader and less slender rays ; much longer and 

 stouter interambulacral spines ; more spinose ventral plates ; and 

 much larger and more numerous marginal spines ; the paxilhe are 

 not so short and thick, and bear fewer and larger central tubercles. 



* We use the term " interambulacral " to designate the first row of plates bordering 

 each side of the ambulacral furrows of starfishes, beheving, as Prof. Agassiz has shown, 

 that they are strictly homologous with the interambulacral plates of Echini. 



TR-A.NS. Connecticut Acad., Vol. I. 35 March, 1867. 



