1032 Bulletin 47, United States National Museum. 



inches. The body is elongated, rather slender, and subfusiform. The head 

 is subconical, entering about 4i times in the total length. The eye is well 

 developed, its diameter being contained 4 times in the length of the side 

 of the head, once in advance of its anterior rim. The posterior extrem- 

 ity of the maxillary bone extends to a vertical line drawn within the 

 anterior rim of the orbit, not quite in front of the pupil. The lower jaw 

 is somewhat shorter than the upper. The first dorsal fin is much longer 

 and lower than the second, to which it is nearly contiguous. Its upper 

 margin is convex. The second dorsal is lower than high, diminishing 

 gradually backward. The caudal, which forms about the sixth of the 

 total length, is somewhat emarginated posteriorly. The anal is placed 

 opposite the second dorsal, and nearly equal to it in size and shape. The 

 ventrals are sublanceolated and rather short, their posterior extremities 

 being even with those of the pectorals, which are subelliptical in their 

 outline. The formula of the fins reads : D.XIV; A. 1, 10; C. 5,1,7,6, 1,8; 

 V. I, 5 ; P. 14. The scales are rather small, deeper than long, anteriorly 

 truncated, posteriorly rounded, with radiating furrows upon the anterior 

 sections only, and fine pectination upon the posterior margin. A series of 

 larger scales conspicuously toothed posteriorly, may be observed along 

 the ventral line between the vent and the extremities of the ventrals. 

 The ground color is reddish brown, the dorsal region being tessellated 

 with blackish spots, whilst a series of black patches may be observed on 

 either side, larger and less numerous in the male than in the female. A 

 black streak intersects vertically the eye. The fins in the male are uni- 

 color, except the first dorsal, which is black, spotted at the base. Jn the 

 female sex the caudal exhibits transverse blackish lines. The inferior 

 regions are unicolor in either sex." (Girard.) (maculatus, spotted.) 



Alvordius maculatus, GIRARD, Proc. Ac. Nat. Sci. Phila., 1859, 67, Fort Gratiot, Michigan. 

 (Coll. B. Alvord.) 



1421. HADROPTERUS ASPRO (Cope & Jordan). 

 (BLACK-SIDED DARTER.*) 



Head 4; depth 5 to 6; eye about equal to snout, 4 in head. D. XIII to 

 XV-11 to 13 ; A. II, 8 to 10 ; scales 9-65 to 80-17, pores 63 to 75. Body 



* The fine gentleman of the family is the Black-sided Darter (Hadropterus axpro). Him we may 

 know by his colors. The ground hue is a salmon yellow; the back is regularly and beautifully 

 marbled with black in a peculiar and handsome pattern. On the sides, from the head to the tail, 

 runs a jet-black band, which is widened at intervals into rounded spots which contrast sharply 

 with the silvery color of the belly; or we may say that on each side is a chain of confluent 

 round black blotches. Sometimes the fishes seem to fade out; these blotches grow pale and no 

 longer meet, but in an instant they may regain their original form and shade. This latter 

 change can be induced by the offer of food, and it is of course due to muscular action on the 

 scales which cover the darker pigment. A male in our aquarium underwent almost instantly 

 an entire change of coloration upon the introduction of a female fish of the same species recog- 

 nized by him as his affinity. Although the two have been together for some weeks, the novelty 

 has not yet worn off, and although his colors vary much from one hour to another, he has never 

 yet quite reverted to his original hues. The form of the Black-sided Darter is more graceful 

 than that of any other, and his movements have little of that angular jerkiness which charac- 

 terizes his relatives. The fins of Hadropterus, like those of Percina, are long and large, the num- 

 ber of dorsal spines being about 14. A notable peculiarity in both species is the presence of a row of 

 shields, or enlarged scales, along the middle line of the abdomen. These may help to protect 

 that part from the friction of the stony bottom. They seem to be shed sometimes, but when or 

 why this happens we do not know. Hadropterus delights in clear running water and maybe found 

 m most streams south and west of New York. It is especially desirable for aquaria, being hardier 

 than any other fish as pretty, and prettier than any other fish as hardy, and witlial with "a way 

 of his own," as au Irish laborer, Barney Mulling, once said to us of Thoreau. Jordan <k Copeland. 



