FAMILY BALISTID.E MONOCANTHUS. 337 



THE THREAD FILE-FISH. 



MONOCANTHUS SETIFER. 

 PLATE L1X. FIG. 194. — (CABINET OF THE LYCEUM.) 



Characteristics. Brownish, with one or more of the anterior dorsal rays elongated into fila- 

 ments. Length five to seven inches. 



Description. Body elongated ; its length exceeding twice its depth, and covered with asperi- 

 ties as in the foregoing species, which extend over the fin rays. Branchial aperture long, 

 oblique, and anterior to the base of the pectoral fin. Tail elongated. Eyes large. The dorsal 

 spine above the posterior margin of the orbits, 0"9 high, with nine white lateral decurved teeth. 

 The dorsal fin with its first ray - 5 long ; its second filamentous, 1 • 3 long ; the third filamen- 

 tous, but shorter than the second ; the remaining rays nearly twice the length of the first, and 

 subequal until we reach the twenty-second, when they gradually decrease in length. I am 

 not sure whether the first ray is entire. Pectorals broad and rounded, with the tips of the 

 rays slightly detached. The rays of the anal increasing in length to the fourth, thence sub- 

 equal to the nineteenth, when they decrease ; the last ray minute. Caudal long and rounded, 

 with flattened rays. 



Color. Dull brownish grey, with obscure darker mottlings on the sides ; beneath rather 

 lighter. Irides yellowish white. 



Length, 5*5. Greatest depth, 2" 1. 



Fin rays, D. 1 .33 ; P. 13 ; V. ; A. 33 ; C. 13. 



This fish, which was taken in the harbor of New- York in August, appears to be undescribed. 

 It bears a certain resemblance to the Cochino of Cuba, described by Parra (p. 15, pi. 9), in 

 its filamentous dorsal, but in other respects is totally different. In some specimens brought to 

 me, the stomach was filled with small crabs, and the first ray only of the dorsal fin filamentous. 



Fauna — Part 4. 43 



