1062 Bulletin 47, United States National Museum. 



premaxillaries very protractile ; teeth on the vomer. Scales thin, ctenoid, 

 little imbricated, present along the region of the lateral line and on the 

 tail, sometimes wanting 011 the back or belly ; lateral line complete, 

 each tube occupying nearly the whole length of its scale. Head scaly or 

 naked; no ventral plates, the belly naked. Gill membranes consid- 

 erably united, forming an angle at their junction. Dorsal fins moderate, 

 about equal to the anal fin and to each other ; dorsal with about 10 

 spines; anal spine single, weak; ventrals well separated, behind pecto- 

 rals, their spines feeble ; pectorals pointed, symmetrical, of 12 to 15 rays. 

 Vertebra? 23 + 21 = 44 ( A. pellucida). Pyloric cceca 4. Frontal region of 

 skull narrow, the parietal region unusually depressed, the bones of skele- 

 ton all slender and thin. Sutures of skull very distinct ; supraoccipital 

 crest obsolete. Foramen of hypercoracoid very large. Darters of mod- 

 erate or rather large size, inhabiting the sandy bottoms of clear streams, 

 where they bury themselves entirely, exceping the eyes and snout. Col- 

 oration translucent, with bright reflections, (a/^of , sand ; npvirrbc , con- 

 cealed.) 



a. Cheeks and opercles scaly; sides of body usually well scaled. PELLUCIDA, 1450. 



oa. Cheeks and opercles naked; body imperfectly scaled. BEANII, 1451. 



1450. AMMOCRYPTA PELLUCIDA (Baird). 



(SAND DARTER.*) 



Head 4 to 4| ; depth 7 to 8*. D. X-10 (IX to XI-9 to 11) ; A. I, 8 to 10 ; 

 scales about 75 (67 to 78), about 6 series above lateral line. Body elon- 

 gate, nearly cylindrical, the flesh pellucid in life, but of firm, wiry tex- 

 ture ; head stout. Cheeks, opercles, and temporal region scaled; the scales 

 embedded and more or less cycloid. Neck above thinly scaled or naked; 

 scales of body not very rough, those along lateral line and caudal peduncle 

 most closely imbricated ; belly entirely naked ; opercle ending in a short, 

 flat spine. Maxillary barely reaching to opposite the large eye ; eyes high 

 up, 3f to 4 in head, nearly equal to snout, separated by a narrow, grooved 

 space. Pectorals shortish, almost as long as head, reaching tips of ven- 

 trals, halfway to vent. Translucent ; scales with fine black dots ; a 



* We have often brought home with us a "Johnny," "Speck," or " Crawl-a-bottom," of a 

 different type from any of those whose habits we already knew. It had a very sharp nose which 

 projected over its mouth; its body was exceedingly slim and round, as transparent as jelly, but 

 hard and firm to the touch. Its belly and much of its back were quite bare of scales and those 

 along its sides were small and inconspicuous. Our aquarium had been arranged for the con- 

 venience of our other Etheostomine friends and the bottom was thickly covered with stones, among 

 which a small fish might easily hide. Several days passed after the introduction of the first Ammo- 

 cn/pta, which survived the change of water, when we noticed that it had disappeared. Careful 

 search among the stones and around the geode only made it the more certain that it had gone and 

 increased our wonder as to the way; for surely it had not been eaten, nor had it jumped out, unless, 

 like Ariel, it could assume a "shape invisible." Finally, after going over every inch of the ground, 

 there was discovered, under the nose of Boleosoma, which was standing, as usual, on its hands and 

 tail, the upper edge of a caudal fin, and on each side of Boly's tail appeared a little black eye set 

 in a yellow frame. Ammocrypta was buried! Was he dead? Slowly one eye was closed in a Darter's 

 inimitable way for they can outwink all animals in creation except owls and a touch of a finger 

 on its tail showed that it had lost none of its activity. It was quite improbable that it had been 

 buried so completely by accident, we therefore cleared of stones a small spot, leaving the hard 

 white sand exposed, and awaited developments. Then for days we watched it closely only to learn 

 that it could bury itself with great celerity, for it was not caught in the act. But our patience was 

 at last rewarded; for one morning, as we came out to breakfast, it put its nose, that we now know 

 nas a tip nearly as hard as horn, against the bottom, stood up nearly straight ou its head and with 



