194 1 CATALOGUE OF FISHES OF TORTUGAS 



53 



Family TRACHICHTHYIDAE 

 Hoplostethus mediterraneus Cuvier and Valenciennes 



The collection contains i specimen, 46 mm. long to base of caudal, in poor 

 condition. Depth in standard length 2.4. D. VI,i3; A. III,io; V. 1,6; scales lost, 

 except the modified ones on the abdomen, which bear spines. 



This species has been reported in the western Atlantic from the Gulf Stream 

 and once from Chesapeake Bay, generally at depths exceeding 150 fathoms. 

 Although the Tortugas specimen is without a definite locality label, it very 

 probably was taken south of Tortugas, where hauls were made in depths as 

 great as about 390 fathoms. S. F. H. 



Family HOLOCENTRIDAE. Squirrelfishes 



Holocentrus ascensionis (Osbeck) 



(Plate 2, figure 1) 



This, largest and most brightly colored of the three Tortugas squirrelfishes, is 

 far more abundant than the casual observer would suppose, as it is most active by 

 night and generally remains hidden by day. Single specimens are exposed to 

 view now and then, but more characteristic are the fleeting glimpses one catches 

 of fish moving in the thick shadow of Acropora or in the semidarkness of deep 

 crevices in massive Orbicella. Sometimes on cloudy days a dozen or so may 

 come out into the open, or a strong ground swell may tug them out. In the dusk 

 of evening they usually leave their retreats, and remain abroad till morning. In 

 a hollow Orbicella on White Shoal, where other shelter was almost completely 

 wanting and where more than a single squirrelfish was never seen at once, one 

 specimen was observed repeatedly during a month, suggesting that these fish, 

 like many others, have places to which they return regularly after a night's 

 foraging. 



In the dead fish the fins, except the spinous dorsal, which is yellowish, are 

 transparent and more or less suffused with red. Head red; body countershaded, 

 with longitudinal stripes of red between rows of scales and separated by pale 

 interspaces. The living fish is not always so red, nor does it always show the 

 simple pattern of the dead, as it may be blotched or clouded with red and silver. 



This species occurs in association with others with which it shares some of its 

 peculiarities of color and structure. For example, a single blast, which probably 

 was not effective beyond a radius of 2 meters, yielded 2 specimens of Holocentrus 

 ascensionis, 2 H. coruscus, and 1 Priacanthus cruentatus. W. H. L. 



This species is most readily distinguished from the other local forms by the 

 smaller scales (about 48 to 52 in lateral series, whereas the others have only about 

 40 to 42). It also has a larger number of gill rakers (13 to 15 on lower limb of 

 first arch, compared with 10 or 11 in the others). Furthermore, the ventrals are 

 longer, extending far beyond the pectorals and reaching the vent. 



West Indies to Florida, also from St. Helena and Ascension Island. S. F. H. 



