RHYACICHTHYID./E 21 



eastern coasts of Mindanao are laved by currents which travel 

 but a short distance from Celebes and Halmahera, with the 

 Sangir Islands and a multitude of reefs between to make still 

 easier the northward extension of their fish fauna. 



This paper contains descriptions of seventy-seven genera, one 

 hundred seventy-three species, and two varieties, of which eleven 

 genera and eleven species are from the China Sea, with no spec- 

 imens as yet known from the Philippines. My assistants, H. 

 R. Montalban, ichthyologist of the Bureau of Science, and Jose 

 Montilla, have given me valuable aid in checking my own field 

 observations in the Ilocano provinces; and Mr. Montalban and 

 G. A. Lopez, collector of the bureau, have obtained large quan- 

 tities of material for study and comparison. I am also under 

 obligations to the provincial authorities of Ilocos Norte, Ilocos 

 Sur, and Abra for courtesies extended, and to many friends in 

 various parts of the Islands for both material and information. 



The illustrations are the work of Pablo Bravo, Marcelino 

 Nievera, Antonino Canlas, and Jose Nievera, young Filipinos 

 who began work under great difficulties and who deserve much 

 credit for their perseverance in working upon such difficult 

 material. 



The given length of specimens does not include the caudal fin 

 unless specifically so stated. The scales in transverse series 

 are counted from the origin of the second dorsal to that of the 

 anal, unless otherwise stated. 



Key to the Philippine families of Gobioidea. 



a 1 . Two separate dorsal fins. 



b\ Ventrals widely separated- Rhyacichthyidse. 



6*. Ventrals not widely separated. 



c 1 . Eyes not stalked; base of pectorals not very muscular. 



d 1 . Ventrals close together, but not united Eleotridse. 



d 1 . Ventrals united to form a disk Gobiidse. 



c*. Eyes very prominent and close together on short stalks; base of 



pectorals very muscular ,. Periophthalmidae. 



a 1 . Dorsals united more or less to form one fin; ventrals united. 



e 1 . No cavity above the opercle Gobioididse. 



e\ A cavity above the opercle Rliy*cichthyidae 



RHYACICHTHYID.E 



This group of fresh-water fishes apparently includes but a 

 single genus, with only one definitely known species. 



It is well characterized by the short, broad, depressed head 

 which, with the long, wide pectorals, forms a well-marked 



