Cycloid AcANTiiorxERES.- 



-FISHES.- 



-ScAnBAED-FISHES. 



135 



f/dlus), called also Oyster-fish, derives its latter desig- 

 nation from its habit of depositing its roe in oyster shells, 

 whose inhabitants have died, or on small piles of pebbles. 



The fish assiduously watches its eggs uiitil they are 

 hatched, snapping at a finger or stick thrust near to the 

 deposit. 



SUB-OEDEE II.— CYCLOID ACANTHOPTERES, oe Acantiiopteees with 



ScoMBEKOiD Scales. 



This s'lb-ordor of Acanthopteros is characterized by 

 Professor Owen in his " Paleontology" as being composed 

 of tcleostiau fishes, having undivided and jointless 

 spines at the fore part of the dorsal, and smooth, circu- 

 lar, or elliptical scales. It is not represented, he says, 

 in the fossil world by any species of older date than 

 the cretaceous epoch. In the present day the Sphyre- 

 noid, Scombride, and Xiphiad iiimilios are its richest 

 groups. Among these, the Tunnies are distinguished 

 by the advanced bony composition of their skeletons, 

 which are, nevertheless, very light, owing to the loose- 

 ness of their texture. 



Many fish of this sub-order are among the most 

 active swimmers of their class, and frequent the sur- 

 face of the wide ocean, keeping at a distance from 

 rocky coasts and surf, with which their delicate scales 

 are ill-fitted to contend. 



Family XXVIL— NOTACANTITS {NotacantMda;). 



This may be considered as an aberrant group of 

 the sub-order, and consists of elongated, compressed 

 fishes, which have (he soapulo-coracoid arch suspended 

 to the back-bone, as in the cartilaginous fishes, and not 



to tlie skull, as in most osseous fishes. They are cither 

 destitute of ventrals, or have these fins situated on tlic 

 belly, and joined together by membrane stretching 

 across. Their dorsal spines are isolated, and the soft 

 dorsal is sometimes wholly absent ; sometimes repre- 

 sented by only two minute rays in the axilla of the last 

 spine ; while in other members of the group, the soft 

 rays are numerous. When the ventrals are present, 

 they are each composed of a spine, and seven or eight 

 jointed rays; but the membrane which connects the 

 rays, and also the two fins to each other, does not, as 

 in the Gobies, form a funnel. Cycloid scales cover the 

 head and body, and partially the fins also. A tapering 

 or conical snout projects beyond the mouth, which is 

 cleft horizontally to a moderate extent. Only slight 

 armature exists on the head, the opercular pieces being 

 hidden under the scaly integument. The tolerably 

 wide gill-openings are situated towards the ventral 

 aspect, being closed above and behind by the scaly 

 integument. The stomach is cecal ; the pancreatic 

 cajca are few ; and the bones contain no osseous cor- 

 puscles. 



The genera are — Nutacanthus ; Mastaccmhtihts, and Klnjii- 

 chohddla. 



Fif. 35. 



Australian Spine-back (Notacauthus ses-splnis). 



The first-named genus is represented by one species 

 ill the Greenland seas, and by another on the coasts of 

 Australia, but none of the family have been detected 

 in the British seas. 



Family XXVIIL— SCABBARD-FISHES 

 (GempyUda:).—V\3.tQ 11, fig. 56. 



The ScABBARD-FlsiiES, or Gempylids, are known 

 by their greatly elongated, compressed bodies, com- 

 bined with more or less of the mackerel aspect ; but 

 they have no corselet on the thorax, neither keel nor 

 armature on the lateral line, and no caudal crests. 



Their heads are low, and their jaw-teeth compresscil, 

 acute, or lancet-shaped, resembling those of the Sphii- 

 rWMi. Palatine and vomerine teeth are present in 

 some of the genera, but absent in others. The ventrals 

 are small and rudimentary, or wholly absent. The 

 skin is smooth and nacry, witliout evident scales, like 

 the belly of a mackerel. Six or seven branchiostegals 

 serve to extend the gill-membrane ; and the stomach 

 is a long, pointed sac— the air-bladder being also long 

 and narrow. 



Most of the members of this family were grouped by 

 Cuvier in an appendix to his first tribe of Scomberoids, 

 named Tricldurini by Bonaparte. 



