DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 215 



Tlii' dorsal fin commences above the rout of the pectoral ami terminates at a short dis 

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

 low, the longest rays, behind the middle of the tin. being noi erectile into a vertical posit ion. 

 The caudal fin (slightly injured) has a rounded margin, and is r ither shorter than the head. 



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

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

 advance of the pectorals. 



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

 present on the cheek only. The upper pari of the head is covered with a thick, spongj 

 skin, as in Centrolophus, 



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



The colors of a fresh fish 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 \)h 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. (Giiittlicr.) 



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 pelagic surface 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 10(1 fathoms. ( "ailing attention to the fact 

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

 adult, he mentions the habit of this and similar forms id' congregating around the floating 

 Medusae, 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 surface oceanic fishes feed voraciously upon various forms of Medusae 

 and upon Sulpn. We have often taken large quantities of this kind of food from the stomachs 

 of various surface Scombroids, as well as from Alutera and Mold. 



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

 at Port Rush, County Antrim, Ireland, in August, 187S, 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." lie says, "the most delicate adult fish 1 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- 

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

 respect to the fishes inhabiting the abyss. 



ICOSTEUS, Lockington. (Figure224). 



Icosleus, Lockin-gtox, Proc. U.S.Nat. Mhs., in. L880,63.- -Jordan and Gilbert, Bull. 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 and 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 jart largest; no teeth on vomer, palatines, or pharyngeals. Gill-rakers 

 flexible, few ; gill membranes separate, free from the isthmus. liranchiostegals (i. 1'seudo- 

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

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



