512 PROCEEDINGS OF THE NATIONAL MUSEUM vol.86 



midlines of the posterior half of the fish, found in the smaller speci- 

 men, is not present on individuals of this length. There is a round, 

 brownish blotch of pigment at the base of each of the ventral fins 

 which extends above the middle of the body. A similar but lighter 

 patch is found at the base of the caudal fin, covering two-thirds of the 

 base. On each segment, except the first two anterior ones, there is a 

 characteristic short bar of pigment below the lateral line. Posteriorly 

 these bars fade and merge into each other. The similar bars found 

 above the lateral line in the larger specimens are not found in fish of 

 this size, although there is a slight indication of them. The pectoral 

 fins are well formed; the rays are formed but are short and do not 

 extend to the base of the ventrals. The ventral rays are also formed 



FiovBE CO.—Macropinna microstoma, new genus and species: Specimen 12 mm long, from station 9530. 



but are likewise short and reach only to the anus. Most of the caudal 

 rays are formed and the hypural plate is present. There is no indi- 

 cation of the dorsal, anal, or adipose fins, although there is a moder- 

 ately large fin fold extending from the vent to the base of the caudal 

 fin and another along the dorsal side from the caudal to above the 

 insertion of the ventrals. The anus is inserted at about two-fifths of 

 the way from the base of the ventrals to the caudal. The intestine 

 extends from the third pigment bar ahead of the base of the ventral, 

 where it emerges from the right side of the stomach, in a straight line 

 to the sixth pigment bar behind the base of the ventrals. At this 

 point the intestine becomes constricted and there is a dextral flexure. 

 The intestine then widens out to form the rectum, and the anus lies 

 below a vertical from between the ninth and tenth pigment bars 

 behind the base of the ventrals. 



16.6 MILLIMETER STAGE (FIG. 61) 



The specimen from station 593B, 16.5 mm in length without caudal, 

 has the typically slender body of the postlarval stages but differs 

 somewhat from the 12 mm specimen. The body is somewhat deeper 

 throughout than that of the latter. The head, snout, mouth, and 

 eyes are the same. The lines of pigment extending back from the 

 corners of the lower jaws are still present. The blotch of pigment at 

 the base of the ventrals is constricted so that it hes over the abdominal 

 cavity but does not extend up on the side of the body beyond the 



