DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 217 



ACROTUS, Bean. 

 Aerotus, Bean, Proc. U. S. Nat. Mns. 1887,631. 



Shape of body as in Tcosteus, from which it differs in the absence of ventrals and 

 spiny tubercles along (lie lateral line, and in having an emarginate caudal. 



Head short; mouth moderate; eye small. Teetb minute, uniserial, on intermaxillary 

 and mandible; vomer, palate, and pharynx toothless. Gill openings wide, the membrane 

 not attached to the isthmus. Gills 4, a wide slit behind the fourth, (iill rakers short, soft. 

 and flexible. Pseudobranchia' well developed. Branehiostegals 6. Vent somewhat in 

 advance of middle of body. Caudal peduncle very slender. Ventrals absent. Caudal 

 large, emarginate. Skin naked. Lateral line without tubercles. Bones all soft and flexi- 

 ble. Size large. 



The genus is represented by a single species, Aerotus Willoughbyi, Bean (loc. tit.), de- 

 scribed from a specimen nearly feet in length cast upon the beach at Quinaielt Agency, 

 Washington, in July, 1887. 



ACROTUS WILLOUGHBYI, Bean. (Figure 225.) 

 Arrotus Willoughoyi, Bean, loc. cit. 



The greatest height of the body at the vent is contained 3^ times in the total without 

 the caudal. The caudal peduncle is very slender; its least beigbt little more than one-third 

 of its length and not much exceeding one-fourth the length of the bead. The length of the 

 head is about one-sixth of the total without caudal. The snout forms one-fourth, the eye 

 one-twelfth, and the interorbital width one-third the length of the bead. The maxilla 

 reaches to below the middle of the eye. The upper jaw is one-third as long as the head. 

 Gill rakers 15, of which 9 are below the angle; the longest about as long as the eye. 



The origin of the dorsal has not been clearly made out; the first ray that can be seen 

 without dissection is nearly midway between the eye and the end of the dorsal, but dissec- 

 tion reveals 7 rays in advance of this. The dorsal begins much nearer the bead in Icostt us, 

 and dissection may show that rays are developed much farther in advance than we have 

 been able to distinguish them. Forty-one rays have been counted in the dorsal, the longest 

 of them little exceeding one-third length of head. The caudal peduncle is as long as the 

 bead without the snout. The caudal is large, emarginate; its middle rays four-sevenths as 

 long as the external rays and two thirds as long as the bead. 



The vent is at a distance from the tip of the snout equal to 3 times, and from the base 

 of the caudal a space equal to 3J times the length of the head. The first evident anal ray is 

 at a distance behind the vent equal to one-sixth length of head. The anal has 38 rays, the 

 longest a little less than one-third as long as the head. 



The pectoral is placed close to the head and nearly in the middle of the height; its 

 length is two-thirds the length of the head; it has 20 rays. 



The lateral line has a slight curve over the pectoral and becomes median about half way 

 between the pectoral and the vent. Skin naked. Peritoneum very dark. 



Color chocolate brown; inside of mouth and gill openings rich, dark brown. 



The type of the species (catalogue number 39340) is o'.'ii inches long. The viscera are 

 wanting. The specimen was obtained at Damon, Wash., July 9, 1887, by Charles Wil- 

 loughby. 



The following extracts from Mr. Willoughby's letter contain additional information 

 about the species:. 



A few days ago I discovered a fish lying on this beach different from any that I have 

 ever seen before. It seemed to be perfectly fresh aud as if it had not been on shore more 

 than an hour. The color of the skin seemed to have been nearly all removed by washing 

 about on the sand. The [pectoral] fin and tail had been partly destroyed. The fish was 

 G feet long. The flesh of the fish is very white, fine grained, aud fat. The fish in color 

 and fatness resembles the black cod. Anoplopoma fimbria. The bones are extremely soft, 

 so much so that the fish can not bear a weight of 5 pounds pulling on it without severing 

 the head. The fish was a female, with a large roe well matured. None of the oldest Indians 

 of the agency have ever seeu anything like it. 





