200 PAPERS FROM TORTUGAS LABORATORY vol. xxxiv 



Its supposed diagnostic characters, generic and specific alike, are spurious. The 

 superior border of snout and nape in the type owes its relative bluntness to dull- 

 ing of the edge by digestion in the grouper's stomach from which it was taken. 

 Erosion along this and other margins, because of their very thinness suffering 

 greatest loss, apparently made the form more elongate and less compressed. The 

 arrangement of scales below the eye is as in normal specimens of X. psittacus. 

 Though most of the scales at the base of the fin have been lost, enough remain 

 to show the line in its usual place, and not a row nearer base of dorsal as has 

 been stated. Between the verticals of the 6th dorsal spine and the 7th ray there 

 are not 8 scales in the lateral line, but between the 6th dorsal spine and the 5th 

 soft ray are 9 lateral-line scales, precisely as in X. psittacus. 



Its compressed body and knife -edged, almost cartilaginous snout and nape 

 enable it to escape pursuit by darting beneath loose sand, and it occurs only over 

 that kind of bottom. Once out of sight it is very difficult to find again, for it can 

 move rather freely under the sand. 



Not only is the species confined to a certain sort of bottom, but most of its 

 members appear to have particular spots to which they return after their rather 

 limited excursions afield. This observation is confirmed by the fact that the same 

 fish may repeatedly lead one to the same place. On the Xyrichthys ground north 

 of Loggerhead Key as many as twenty selected spots, marked and protected, may 

 be seen at once by a diver. On each, when the work is complete, stands a conical 

 mound of coral fragments, which may measure as much as 14 or 15 inches in 

 diameter at the base, rise to a height of 6 inches, and enclose a crater 3 or 4 inches 

 in diameter, whose bottom is loose stirred sand. 



Xyrichthys picks up and tosses its material into position, handling it in an 

 orderly way, with determinate and serviceable results. If pieces from the rim of 

 its building be toppled into the pit, they are removed and laid again in position. 

 So it seems that such a shelter is heaped up with considerable expenditure of 

 effort, is kept more or less in a state of repair, and is a semipermanent habitation, 

 usually occupied, I think, by one fish only, which may often be seen resting 

 beside or above it. 



The adult male differs from the female in the steeper profile, and his ventral 

 fins nearly or quite attain the anal origin, whereas hers fall a little short of the 

 vent. The male is olive-buff dorsally, with a dusky area below the lateral line 

 and beneath the 7th dorsal spine, lying in one of five bands rather distinctly de- 

 fined when the fish rests, but shown faintly, if at all, when it swims; side of the 

 head vertically streaked with blue on a ground of faint olive; two rows of scales 

 at base of dorsal shimmering with pale blue, and every other scale on the side 

 with a sharply drawn thin vertical line of blue at its base; median fins poppy red, 

 darker toward outer or hinder margin; caudal with rather faint transverse 

 wavering lines of blue; anal with stronger wavering lines of blue; iris blue with 

 a ring of orange or yellow at the pupillary border. 



In the female the dorsal ground color is vinaceous buff; the dorsolateral spot 

 small and very faint; vertical blue lines on scales of sides diffuse and indistinct; 

 pattern drawn more firmly on anal in female, in strokes cutting the rays sharply 



