600 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 



with the greater number of dorsal spines, and with their northern 

 habitat. These are the only Labroids properly belonging to the north 

 temperate zone, a\nd all but two of the species are European. 



The Malapterince seem to be allied to the Labrinw, although they may 

 belong to some other family. The number of vertebrae have not been 

 counted in the single known species. It belongs to the South Tem- 

 perate Zone, and differ from the Labrinw iu having most of its dorsal 

 spines replaced by soft rays. 



The Harpince are allied to the Labrinw, but are chiefly tropical fishes 

 with a reduced number of vertebrae and spines. Close to the Boctianincc 

 is the small subfamily of Clepticince, distinguished by the little develop- 

 ment of the jaws and pharyngeals and by the correspondingly feeble 

 dentition. 



The Julidince are the most abundant of the tropical Labroids, brilliant 

 little fishes, abounding about banks and reefs, and having the vertebrae 

 reduced to the normal number 10-f- 14=24 and the dorsal spines to 

 about nine. 



The Scarince are almost exclusively tropical. They have the normal 

 number of vertebrae and of spines. Their pharyngeal bones and teeth 

 are, however, modified in a very singular way, and they must be re- 

 garded as forming the most specialized type of Pharyngognathi, the 

 suborder to which the Labroids belong. Professor Cope regards this 

 suborder as the most specialized or a highest" in the group of fishes. 

 The specialization of the Labroids is, however, reducible to two or three 

 characters, the specialization of the pharyngeal bones, the gills, and 

 in general of the pigment cells. In general they are not less generalized 

 than the majority of the Acanthopteri, and they do not depart so widely 

 from the usual fish type as do the Pediculati, Plectognathi or Heteroso- 

 mata. 



NUMBERS OF VERTEBRA. 



The fact that northern forms have an increased number of vertebrae 

 is well shown in this group. The following table shows the numbers of 

 vertebrae as given by Doctor Gunther* in the species examined by 

 him. 



* " It will be evident that in those genera which are composed entirely or for the 

 most part of tropical species, the vertebral column is composed of twenty-four or 

 nearly twenty-four vertebrae, whilst those which are chiefly confined to the temper- 

 ate seas of the Northern or Southern hemisphere have that number increased in the 

 abdomiual and caudal portions." (Giiuther, iv, §5.) This increase in the number 

 of vertebrae in northern forms has been used as a basis of the classification of tbe 

 Pleuronectidce,by Jordan & Goss, of the Scorp(vnidce,hy Jordan & Gilbert, and it will 

 doubtless prove to have a high value in the subdivision of other families which have 

 representatives in different zones. The cause of this peculiarity of fishes of cold 

 waters is still obscure. Probably the reduction iu number of segments is a result of 

 the specialization of structure incident to the sharper competition of the tropical 

 waters, where the outside conditions of life are very favorable for fishes, but the 

 struggle of species against species is most severe. 



