112 BULLETIN OF THE BUREAU OP FISHERIES. 



posterior to the yolk sac, not at the margin, but laterally near the base of the ventral- 

 fin fold. The depth of either dorsal or ventral fin fold is greater than the depth of the 

 body posterior to the vent. Black chromatophores occur sparsely scattered over the 

 head and anterior trunk region and on the oil globule. Two small groups occur 

 also near the margin of the dorsal-fin fold. A small yellow area occurs laterally just 

 posterior to the otocyst. Farther posteriorly the body is marked by two vertical 

 bands of black and yellow pigment, one of which is located a short distance posterior 

 to the vent and the other somewhat more than half the distance from the vent to the 

 posterior end of the body. 



All the newly hatched larvae kept in the laboratory died within 24 hours. Neither 

 were larvae of this species taken in the plankton. The later stages here described were 

 selected from specimens taken by W. W. Welsh at or near the surface at the Grampus 

 station 10258, August 25, 1914, about 20 miles south of Marthas Vineyard, Mass. 



A young fish 6.5 mm. in length is illustrated in figure 55. At this stage the head is 

 relatively large, and the body tapers gradually toward the posterior end. The lateral 

 position of the vent is still apparent. The dorsal region of the abdominal cavity is 

 heavily pigmented. Large black chromatophores occur on the dorsal aspect of the 

 head and the anterior region of the trunk. The body is marked further by a vertical 

 band just posterior to the vent, another approximately halfway from the vent to the 

 posterior end of the body, and a third near the posterior end of the body. 



In young fish 11 mm. in length (fig. 56) the head remains relatively large. The 

 dorsal, anal, and caudal fins are becoming well differentiated. The dorsal region of the 

 abdominal cavity remains heavily pigmented. Large black chromatophores now occur 

 along the entire dorsal aspect of the body except in the caudal region. The three ver- 

 tical bands described above are still present but are less distinct than in the earlier 

 stages. 



In young fish 20 to 25 mm. in length (fig. 57) the pigmentation characteristic of 

 the earlier stages is no longer apparent. The dorsal and dorsolateral aspects of the 

 body are more or less uniformly, but only lightly, pigmented. The head is long and the 

 body is relatively slender. The young fish are now gradually assuming the general 

 appearance of adults and already show some of the diagnostic characters of the species. 



PORONOTUS TRIACANTHUS (Peck). BUTTERFISH. 



Spawning. — The spawning habits of this species are practically unknown. The 

 data available indicate that these fish leave the inshore waters during the spawning 

 season. In the Woods Hole region, there is a run of fish in June, lasting a week or longer. 

 After this relatively few butterfish are taken in the inshore waters until about Septem- 

 ber I, when they again become abundant. During the first half of July, 1915, adult 

 butterfish were taken in considerable numbers and daily examinations made. The 

 majority of the males were ripe for stripping, and many of the females were apparently 

 nearly ripe. However, mature eggs could not be obtained. After July 15 the catch 

 gradually fell off until relatively few butterfish were taken. The majority of these 

 were smaller than those taken early in July. About August 15 fish of larger size again 

 were taken, but these were spent. At this time schools of butterfish were reported 

 offshore. 



