DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 215 



The dorsal fin conimeuees above the root of the i)ectoral and terminates at a short dis- 

 tance from the caudal, the caudal peduncle being about as deep as long. This fin is rather 

 low, the longest rays, behind the middle of the fin, being not erectile into a vertical position. 

 The caudal flu (slightly injured) has a rounded margin, and is rather shorter than the head. 



The pectoral flu has a broad base, is more than half as long as tiie head, and has the 

 upper rays longer than the lower. Ventrals rather small, close together, and inserted in 

 advance of the pectorals. 



The entire flsli is covered with minute, cycloid scales; on the head they appear to be 

 present on the cheek only. The upper part of the head is cov-ered with a thick, spongy 

 skin, as in Centrolophn.s. 



Radial formula: D. 38-50; A. 25-29. 



The colors of a fresh flsh are a pale greenish olive, marbled with darker, the markings 

 being in the form of spots on the upper, and of irregular longitudinal bands on the lower 

 half of the body. Also the vertical fins are spotted with blackish. The iris is nearly white, 

 and a ring of small white pores encircles the orbit. 



The specimen described is 9^ inches long and in good condition, with the exception of 

 the lower part of the abdomen, which is lacerated and shrunk in consequence of the loss 

 of the intestines. All parts of the body are in that state of softness which is peculiar to 

 many deep-sea fishes. (Giinther.) 



Adult specimens have, according to Giinther, been obtained in the Mediterranean, one 

 on the coast of Ireland, and another in the South Sea, near Samoa. 



This is primarily a ijelagic surlace form, but it seems very possible that it inhabits the 

 middle or lower strata of the ocean as well. Dr. Giinther says that it is evident that at 

 least in the adult state it descends to some depths. The want of firmness in the tissues 

 seems to clearly indicate it as a deep-sea fish. He hazards the opinion that the depth to 

 which it may descend, probably does not exceed 100 fiithoms. Calling attention to the fact 

 that the young of the species are nuich more frequently found near the surface than the 

 adult, he mentions the habit of this and similar forms of congregating around the fioating 

 Medusie, and also questions the accuracy of the theory that fish ever feed upon Medusa;, 

 since he says the fish could draw but little nourishment from these animals. As a matter 

 of fact, many of our surtace oceanic fishes feed voraciously upon various fi)rms of Medusit; 

 and upon Sfdpd. We haveoften takenlargC(iuantitiesof this kind of food from the stomachs 

 of various surface Scombroids, as well as from Alitfcra and Mola. 



Dr. Giinther's full description, which is quoted above, is taken from a specimen obtained 

 at Port Kush, County Antrim, Ireland, in Aitgust, 1878, captured in a salmon net. Mr. 

 Ogilby, who sent it to the British Museum, was very much impressed by the softness of the 

 flesh. "It was," he says, "the most delicate adult flsh I ever handled; so much so, that 

 within twenty-four hours after its capture the skin of the belly and the intestines fell off 

 when it was lifted, and it felt in the hand quite soft and boneless." This is quoted to em- 

 Ijhasize what has been said regarding the softness of its tissues, and its similarity in this 

 respect to the fishes inhabiting the abyss. 



ICOSTEUS, Lockington. (Figure 224). 

 IcoKteim, Lockington, Proc. U.S. Nat. Mas., in, 18.S0,G3.— .I()RDAX;uid(;iiJiKRr, Hull. XVI, U.S.Nat. Mus., 618. 



Body oblong, much compressed throughout, the head thicker than any part of the body. 

 Dorsal outline rising rapidly to the origin of the dorsal fin, thence more regularly curved; 

 the region at the base of the dorsal aud anal strongly compressed; caudal peduncle slender, 

 widened at the base of the fin. Mouth large, horizontal ; maxillary narrow, reaching to 

 beyond middle of eye. Teeth in jaws in one row, slender, sharp, closely and regularly set, 

 those in the lower jaw largest; no teeth on vomer, palatines, or pharyngeals. Gill-rakers 

 flexible, few; gill-membranes separate, free from the isthmus. Branchiostegnls 6. Pscudo- 

 branchia; well developed. Lateral line conspicuous, continuous, decurved, groups of small 

 spines present along its entire length. No scales anywhere on body or fins. Fins rough, 



