ECHINOLAMPAS STERNOPETALA. 115 



distinct loop on the base. In the other, the valves (PI. 144, fig. 16) are straighter 

 and narrower; they lack both teeth and loop. In both forms, the valves range 

 from .25 to .40 mm. in length. 



Echinolampas depressa. 



Gray, 1851. Proc. Zool. Soc. London, p. 38. 



Plates 144, figs. 18, 19; 153, fig. 8. 



This is the West Indian species of the genus and there is little reason to 

 doubt that de Meijere's record of it from near Saleyer, Dutch East Indies, 

 is a case of mistaken identification. Very likely the Siboga specimens represent 

 an undescribed species. Ophicephalous and tridentate pedicellariae occur 

 in depressa but no triphyllous were found. The ophicephalous have the valves 

 (PI. 144, fig. 19) somewhat smaller than those of alexandri and the blade is less 

 rounded. The tridentate are all of one kind with valves (PI. 144, fig. 18) .25- 

 .45 mm. long, having the blade a little widened, flattened and serrate at tip. 



Echinolampas sternopetala. 



A. Agassiz and Clark, 1907. Bull. M. C. Z., 51, p. 130. 



Plates 144, figs. 20-24; 147, figs. 1, 2; 153, figs. 5-7. 



The available specimens measure 43-53 mm. in length, 36-44 mm. in 

 breadth and 19-22 mm. in height. The breadth averages about .85 of the 

 length and the height averages not quite .45 of the length. The abactinal 

 portion of the ambulacrum is not at all petaloid and the part of the poriferous 

 area having paired pores is not distinctly indicated. Indeed owing to the 

 fact that the lateral margins of the ambulacra are strongly purple-tinted, a 

 careful examination is necessary to determine the number of pore-pairs. In 

 the holotype (PI. 153, fig. 5) ambulacrum III has 27 pore-pairs on the left- 

 hand side and 30 on the right, while in a specimen very little smaller (PI. 147, 

 fig. 2) there are only 12 on the left and 17 on the right. In the holotype, ambu- 

 lacrum II has 27 pore-pairs on the left and 37 on the right, while the smaller 

 specimen has 12 and 29 respectively, a remarkable disparity. In the holotype, 

 ambulacrum I has 32 pore-pairs on the left and 25 on the right, while in the 

 smaller specimens the figures are 24 and 12. The longer poriferous area in 

 each of these three ambulacra are in the holotype 12, 15, and 15 mm. respectively 



