WEST INDIAN STARFISHES 163 



dorsal pore at the apex. Radii 9°^°" and 28°"°^, marginal plates 

 17-18 on a side. 



Teratology. 



A medium sized specimen taken on the Great Bahama Bank by 

 the Bahama Expedition, May 17, is quite unlike any other that 

 I have seen, in some respects. The radii are 14°^^ and 53°^°^; 

 breadth of rays at base, minus spines, 15"^™ ; breadth of paxillar 

 area at 2d marginal plate, 4™™. Number of superomarginal 

 plates 17 to 18 pairs. The marginal plates are unusually large 

 and thick, well rounded, rising up considerably above the nar- 

 row paxillar area and separated by wide, straight, fasciolated 

 grooves. The radius of the disk is equal to five marginal plates. 

 The two interradials are particularly large and swollen, except 

 in one interradius where they are narrower and separated par- 

 tially by an unpaired intercalated plate, bearing a small conical 

 spine. Small conical spines are present on the outer side of 

 more or less of the plates on the distal part of the rays, but are 

 entirely lacking on some distal plates, but they extend proximally 

 in some cases to the second plate and on one side of one ray to 

 the first plate, which bears also a second similar spine at the sum- 

 mit. A few other short spines of the inner series occur on the 

 first and second plates, thus approaching the condition seen in 

 A. dicplicatus, but these spines are few, small, and irregular on 

 this specimen. The inf eromarginal spines are flattened, as in the 

 type, mostly two, but proximally three, subequal, on many plates. 



The spinulation of the under side, including the adambulacral 

 plates, is essentially the same as in the typical specimen of A. 

 articul-atiis, described above. 



Mr. Ives (op. cit., 1891) stated that the species described by 

 Liitken and that figured by A. Agassiz, as A. articulatus, are dif- 

 ferent, and that the latter represents A. duplicatus Gray. 



I do not agree vrith. either of these propositions. The general 

 fi:gures by Agassiz accurately represent the species found on the 

 coasts of North Carolina and Florida, when in perfect preserva- 

 tion, and agree entirely in all essential points with the descrip- 

 tions by Say and Liitken, even to the row of small conical supero- 

 marginal spines on the distal part of the rays only — a charac- 

 teristic feature mentioned both by Say and Liitken. 



