DISCOBOLI. 179 



Family, XIX— DISCOBOLI (part), Cuvier. 



Body rounded, transversely expanded or oblong. Teeth minute. Gill-openings 

 narrow. Grill-membranes attached to the isthmus. Grills, three and a half. 

 One or two dorsal fins, the anal being similar to the second dorsal. Ventrals 

 each with one spine and five rudimentary rays, which form the centre or 

 framework of a round suctorial disc, which has a skinny outer margin. Air- 

 bladder absent. Pyloric appendages numerous, or in moderate numbers. 



Cuvier's Discoboli included the Gobiesocidce in addition to the fishes as here 

 restricted, which having their ventral fins forming a suctorial disc allies them to 

 the gobies. They have been divided as follows : — 



A. Two separate dorsal fins — Cyclopterina. 



B. One dorsal fin : the infraorbital ring of bones not articulating with the 

 preopercle — Liparidina. 



Geographical distribution. — Mostly littoral and carnivorous fishes, some of 

 which are of a small size, while all can attach themselves to rocks or other 

 desirable objects by means of their suctorial discs. They are found from the 

 Arctic Ocean to the more temperate regions of Europe and America. 



Genus I. — Ctclopterus, Linnceus. 



Lumpus, Cuvier. 



Branchiostegals six : pseudobranchice present. Body short, thickened, and more 

 or less elevated. Villiform teeth in the jaws, none on the palate or tongue. Gill- 

 openings narrow, the gill-membrane being attached to the isthmus : gills three and 

 a half. Two dorsal fins, the anterior, which may become more or less atrophied in 

 the adult, is formed of flexible spines. Ventral consisting of one spine and five rays, 

 the two united so as to form a somewhat circular disc. Second dorsal opposite and 

 nearly similar to the anal. Shin loose, viscous, having tubercles in rotvs as well as 

 scattered. Skeleton but slightly osseous. 



Gill has instituted genus JHumicrotremus for the reception of Cyclopterus 

 spinosus of Fabricius. 



Geographical distribution. — As observed for the Family. 



The modification of the ventral fins into a suctorial disc enables these fishes 

 to inhabit regions which would otherwise be fatal to their existence, as during 

 storms should they not be firmly attached to some unjdelding substance, their 

 umvieldly bodies would soon be beaten to death by the waves or dashed on to the 

 shore. Mr. A. Wilson (Nature, June 26th, 1879) suggests whether this sucker 

 may not have been developed by natural selection as an useful adjunct to the 

 breathing movements of the fish, as when fixed it appeared to be perfectly at 

 its case, and to breathe more fully and strongly than when swimming about. 



1. Cyclopterus lumpus, Plate LV. 



Cyclopterus gibbosus, Willnghby, p. 209, t. N 10, f. 2. ~Lumpus Anglorum, 

 Aldrov. iii, c. 68, p. 479 ; Jonston, i, tit. 1, c. 3. art. 3, punct. 12, p. 42, t. xiii, 

 f. 1 ; Willughby, p. 208, t. N 11 ; Bay, Syn. p. 77. Lepus marinus, Schonev. 

 p. 41. Cyclop.'jrns, sp. Artedi, Gen. p. 62 ; Gronov. Mus. Ich. i, p. 56; Gouan, 



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