INTRODUCTION. xi 
physoclists with abdominal ventrals (Catosteomi and Percesoces) is, I feel, much 
in need of revision, and it may be found advisable to break up this group [Catosteomi|] 
into a greater number of sub-orders.” 
I have paid a good deal of attention to these groups, and am of opinion that they 
are unnatural and indefinable. 
After removal of the Selenichthyes, which I have recently been able to show are 
related to the Teniosomi, and of the Hypostomides, the remainder of the Catosteomi, 
which corresponds to the Hemibranchii of Smith Woodward, is still a heterogeneous 
assemblage which I find incapable of definition, and includes three well-marked but 
probably related groups which should, in my opinion, be given sub-ordinal rank. 
These are: (1) THoracoste1*, which have on each side a large dermal plate, which 
in the adult is co-ossified with the coracoid and suturally united to the clavicle ; 
(2) SoLENICHTHYES (nom. nov.), which have a considerable amount of dermal armour 
but no plates similar to the ectocoracoids of the Thoracostei—the tubiform snout, 
terminal toothless mouth, pectinate gills, and elongate anterior vertebre with separate 
transverse processes further characterize this group; (3) LopHosrancuil, differing 
from the Solenichthyes in the lobate gills and normal anterior vertebre. 
The resemblances between the Centriscide and the Solenostomide, respectively 
the most generalized of the Solenichthyes and the Lophobranchii, seem to indicate 
relationship, but are, no doubt, in great part due to similar modes of life. 
A few fishes belonging to the sub-order Lophobranchii are found in the rivers 
of Mexico and Central America. 
Adding the Osphromenide, which should, in my opinion, be placed with the 
Anabantide, and after removing the Scombresocide to the Haplomi, the Ammodytide 
and Champsodontide to the Percomorphi, and the Chiasmodontide (incert@ sedis), the 
families included by Boulenger in the Percesoces may be arranged thus :— 
I. Pelvic bones remote from the clavicles; a separate spinous dorsal; no supra- 
branchial organ; no esophageal sacs. «ww ee ee ee) Atherinide, Mugilide,, 
Polynemide, and Sphyrenide. 
II. A suprabranchial organ. . . . . . . Ophiocephalide, Anabantide, and Osphromenide. 
III. Gsophagus with a pair of lateral muscular sacs, with internal papille which 
may be toothed. . . 2. 2 2 e+ «© 6 © © © e es « Letrayonuride, Stromateide. 
IV. Pelvic bones remote from the clavicles; no fin-spines; no suprabranchial 
organ; no cesophageal sacs... 1. 6 6 6 1 ee we ew ee we + LeOsteide. 
In the second and third of these divisions we see the transition from abdominal 
* Swinnerton, Quart. Journ. Micr. Sci. xlv. 1902, p. 580, and xlix. 1905, pp. 369-380. 
b2 
