636 TELEOSTEI CHAP. 



Five or six species, referable to two genera, Pegasus and 

 Parapegasus, make up this family. They are very small fishes, 

 inhabiting the coasts of China, Japan, Arabia, the Malay Archi- 

 pelago, and Australia. Pegasus is remarkable among all fishes 

 in having the five anterior rays of the pectoral fin transformed 

 into strong spines. 



Sub-Order 8. Percesoces. 



Air-bladder, if present, without open duct. Parietal bones 

 separated by the supraoccipital. Pectoral arch suspended from 

 the skull ; no mesocoracoid arch. Ventral fins, if present, abdo- 

 minal, or at least with the pelvic bones not solidly attached to 

 the clavicular arch. 



This group connects the Haplomi with the Acanthopterygii, 

 the Scombresocidae being somewhat related to the Cyprinodonts, 1 

 whilst the Anabantidae show distinct affinity to the Osphro- 

 menidae in the following sub-order. Other families, previously 

 included among the Scombriform Acanthopterygians, are placed 

 here on the assumption that the loose attachment of the pelvic 

 bones to the clavicles is a primitive character, and not the result 

 of degeneration, such as occurs in some cases among true Acan- 

 thopterygians. Although this sub -order is perhaps only an 

 artificial association, it must be borne in mind that, notwith- 

 standing the very wide divergence which exists between the first 

 and last families, and however dissimilar their members may 

 appear to be at first sight, a gradual passage may be traced con- 

 necting the most aberrant types. 



SYNOPSIS OF THE FAMILIES. 



I. Ventral fins, if present, inserted far behind the pectorals ; no spines to 

 the fins. 



Ribs attached to the extremity of much-developed parapophyses ; lower 

 pharyngeal bones completely united ; pectoral fins inserted very high up 



1 . Scombresocidae. 



1 Swinnerton (Quart. J. Micr. Sci. xlv. 1902, p. 554) lias pointed out that the 

 skull of the Scombresoces belongs to what he terms the Acrartete type (i.e. in 

 which the attachment of the palatine cartilage or its derivates is confined to the 

 pre-ethmoid cornua), whilst the other Percesoces examined by him, as well as the 

 Cyprinodonts are Disartete (the attachment being at the parethmoid and pre- 

 ethmoid cornua) ; but the character is so indistinctly defined in some adult 

 Cyprinodonts that I feel some diffidence in making use of this character for 

 systematic purposes in the present state of our knowledge. 



