NO. 5 CLARK : ECHINI OF WARMER EASTERN PACIFIC 335 



Encope fragilis^^, new species 

 Plate 60, Figs. 56-57 



Test rather fragile, 124 mm long, 130 mm wide and 10 mm high; 

 greatest thickness just a little back of tip of unpaired petal which is 30 mm 

 long and 14 mm wide; poriferous zones wide, the two equal in width to 

 the median area; pore-pairs crowded, the narrow ridges between them 

 covered b}^ a single series of 20-24 minute tubercles ; closed tip of petal 5 or 

 6 mm from anterior lunule which is 8 mm long and about 1.5 mm wide; 

 its tip 8 mm from disk margin. Anterior paired petals about 26 mm long 

 and 13 mm wide; they point directly to anterior lunules which are about 

 10 mm from their tip and measure 12 mm long by 2 (or less) wide. Pos- 

 terior petals almost duplicates in size and form of the unpaired one. 

 Posterior lunules about 15 mm long, 2.5-4 mm wide. Interambulacral 

 lunule very large, 20 mm long by 8 mm wide, only about 8 mm from 

 margin. Lower surface of test perfectly flat but not peculiar. Spines of 

 abactinal surface very numerous, slender with abruptly bulbous tips lying 

 almost horizontal, forming a delicate smooth coat ; spines around lunules 

 long and pointed, those of lower surface slender, pointed or blunt or even a 

 bit widened at tip. Light brownish olive above, brightest on the petaloid 

 area and on the lunule margins, darkest at disk margin ; faintly outlining 

 many plates are dark, Andover green lines, fonning an indefinite but more 

 or less evident pattern ; lower surface a tawny olive. 



In addition to the symmetrical and handsome holotype there are 5 

 other Encopes clearly belonging to this striking species. The smallest 

 measures 80 x 80 mm with a thickness of 8 mm ; the anterior and left 

 posterior lunules are not completely closed in ; a less symmetrical specimen 

 is 90 X 88 mm and has both the right hand lunules open ; a very symmetri- 

 cal specimen, 90 x 92 mm has all the lunules fully closed ; a very unsym- 

 metrical and irregular adult is approximately 135 mm long and 125 mm 

 wide; no lunule is closed in save the anterior which is imperfectly shut in. 

 The largest individual is 154 mm long, 152 mm wide and 11 mm thick 

 (35-40 mm back of the anterior margin) ; the dull greenish lines are 

 present but much less evident than in the holotype. Of the smaller speci- 

 mens only one gives any indication of them. 



Distribution. — Most of the material referable to this very striking 

 species was taken in or near Petatlan Bay, Mexico, at 5 stations. The 

 holotype is from Station 764-38, near White Friars Rocks, Mexico, in 

 15-20 fms; the largest specimen and the very irregular adult mentioned 

 above are from Station 963-39, nearby but in slightly deeper water (20-25 



^^ fragilis=easUy broken, in reference to its relatively delicate structure. 



