1919.] NATURAL SCIENCES OF PHILADELPHIA. 155 



lobe marginally pale gray, upper darker. Anterior to vent dark 

 body color mostly purplish-gray, posteriorly brownish. Ventral 

 neutral dusky with very narrow pale edge behind. Length 133 

 mm. 



The above example of this rare fish was found on an adult Isti- 

 ophorus nigricans captured in the Gulf Stream 1^ miles south of 

 Fowey Rock Light, Florida, in March, 1919. It was secured for the 

 Academy by Mr. Morgan Hebard. He tells me the Istiophorus 

 was 6 feet 8 inches long and when hauled on board the Rhomhochirus 

 continued to adhere to the post-pectoral region of its host, remaining 

 quiet. When pulled off b}^ the tail it became quite active. Mr. 

 Hebard also notes that in life the color had a smooth and immaculate 

 mouse-brown appearance, strikingly marked about the pectoral, 

 head and disk with whitish. While alive these markings were 

 sjmimetrical, though now as described previously, the change took 

 place immediately after death. In life the pectorals had 

 conspicuous dark borders and pale centers. 



Valenciennes figures the species from the sea of the Antilles, show- 

 ing the dorsal origin about midw^ay between the sixth dorsal lamina 

 and the caudal base, color largely uniform brownish with neutral 

 tints or only disk pale, pectoral brown, ventral pale or gamboge and 

 the eye much smaller than in my example. ^^ Poey examined several 

 examples which he named Echeneis tetrapturorum^^ up to 300 mm. 

 long. As may be inferred, Poey's examples were all from Tetrapturus, 

 while the present one seems to indicate a new host for the species. 



^' Cuv. Regne Animal (Ed. 111.,) 1839, 312, PL 108, fig. 3. 



36 Mem. Hist. N. Cuba, II, 1858, p. 256, PI. 18, fig. 2 (pectoral fin). Cuba. 



