2 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



therefrom into fresh water, (2) pass most of their life in the sea and 

 enter fresh water only at certain seasons for spawning or other pur- 

 poses, and (3) occur indifferently in fresh or salt water. However, in 

 order that this work may be more generally useful it will be made to 

 include all species that may be found at any time in fresh water. 



The scope of the title will be further broadened to include the 

 gobies and catfishes; all local species will be considered whether or 

 not they may be strictly fresh-water denizens, as, for several reasons, it 

 has been thought desirable to present these families as a whole. 



The publication of this catalog by no means implies that the sub- 

 ject is exhausted or that there is no need for future investigation. On 

 the contrary, it is hoped that the present publication may serve as a 

 stimulus to further study, which will throw much needed light on the 

 bionomics of the known species and bring to notice many forms that as 

 yet are unnamed. The vastness of the fresh waters of the plains areas 

 and the remoteness and isolation of the innumerable mountain streams 

 guarantee that for many years to come important work may be profit- 

 ably undertaken by governmental agencies and by individuals. Fur- 

 ther collecting is especially desirable in the streams of the western side 

 of Peninsular Thailand, in streams contiguous to the Malay States, in 

 the Menam Mun and its tributaries in Eastern Thailand, in mountain 

 streams of the eastern slope of the Peninsula, and in streams of the 

 western frontier east of Moulmein. 



The classification, the arrangement of families and genera, and 

 the terminology herein followed are in general in conformity with 

 "The Fishes of the Indo-Australian Archipelago," by Max Weber 

 and L. F. de Beaufort (vols. 1 to 8, 1911 to 1940), with such modifi- 

 cations as appear to be warranted or demanded by the more recent 

 taxonomic studies and conclusions of various ichthyologists. Full 

 descriptions of families, genera, and species have in general been 

 omitted because they are available in the Literature Cited and would 

 unnecessarily swell the bulk of the catalog. The artificial keys are 

 believed to be sufficiently full and explicit to enable qualified persons 

 to allocate and identify any species that may come to hand in field, 

 laboratory, or museum. The keys should, of course, be used with 

 proper discrimination and with due allowance for variations depend- 

 ent on size, age, sex, breeding condition, and individual departure from 

 the normal. 



The synonymy includes practically every published citation of a 

 Thai species or locality. The form of the citations has been abbre- 

 viated from the full references given in the Literature Cited. The 

 synonymy has been restricted to citations pertaining to Thailand, ex- 

 cept in a few special cases in which there may be reasons for giving 

 references to nearby countries. 



