750 Bulletin 47, United States National Miiseum. 



as snout and eye, or even longer in some specimens; serrate at base and 

 with basal cusp ; ventral plate as long as spine in many specimens, nar- 

 row, the greatest width 2 to 2i in length. Lateral armature complete, 

 the plates gradually reduced in size posteriorly, forming a distinct caudal 

 keel. Dark grayish or bluish black above, silvery below, with a few dark 

 punctulations, thickest on caudal peduncle and near tip of ventral spines. 

 San Francisco to Alaska and Kamchatka; very abundant northward; 

 rarely or never entering fresh water. Very close to Gasterosteus Mspinosus, 

 and only distinguishable by the more robust form ; probably both of them 

 to be regarded as geographical subspecies of Gasterosteus aculeatus, and 

 perhaps not really recognizable at all. (/earu^pa/crof , cataphractus, mailed.) 

 Gasteracanthus cataphractus, PALLAS, Mem. Acad. Petersb., in, 325,1811, Kamchatka. 

 Gasterosteus obolarius, CUVIER & VALENCIENNES, Hist. Nat. Poise., iv, 500, 1829, Kamchatka. 

 Gasterosteus insculptus, RICHARDSON, Last Arctic Voyage, 10, piato xxv, figs. 1, 2, and 3, 1854, 



Northumberland and Puget sounds. 

 Gasterosteus serratus, AYRES, Proc. Cal. Acad. Sci., 1855, 47, San Francisco; SAUVAGE, Revision 



des tipinoches, 13, 1874. 



Gasterosteus inlermedius, GIRARD, Proc. Ac. Nat. Sci. Phila., 1856, 135, Cape Flattery. 

 Gasterosteus aculeatus cataphractus, JORDAN & GILBERT, Synopsis, 396, 1883. 



1101. GASTEROSTEUS WILLIAMSONI, Girard. 



Head 3J to 3^ ; depth 3^ to 4 ; eye 3i to 4 ; snout = eye. Dorsal II, I, 

 10 ; anal I, 8. Body short and deep, not especially compressed ; head 

 small ; mouth small, not quite as obliqua as in var. microcephalus ; maxil- 

 lary not reaching eye ; caudal peduncle deep and stout, not keeled. Pro- 

 cesses from shoulder girdle widely divergent, inclosing a large triangu- 

 lar area. Naked area in front of pectoral narrow. First and second 

 dorsal spines very short and weak, li to 2 in distance from tip of snout 

 to pupil, the first not reaching the second when depressed, and the 

 second falling far short of the third ; ventral spines short and stout, 

 about equal to snout, broadened at base, serrate on outer side, cusp 

 sometimes present ; ventral plate broad, longer than spines, about as 

 long as snout to posterior edge of pupil. Sides nearly always without 

 armature, occasionally 2 or 3 anterior plates developed, which is accom- 

 panied by a greater development of the dorsal and ventral spines. 

 Dusky, sides paler and mottled. Males with the head bright coppery 

 red. This description is based upon numerous specimens collected in 

 Santa Ana River, at Colton, California, by Dr. Charles H. Gilbert. 

 Fresh-water streams of southern California ; locally very abundant, 

 replacing microcephalus inland ; Williamson Pass ; San Bernardino (Rosa 

 Smith). This form is apparently derived from G. microcephalus, and is 

 usually well distinguished. (Named for Lieut. R. S. Williamson, a mem- 

 ber of the United States Pacific Railroad Survey, by whom the species 

 was first obtained.) 



Gasterosteus williainsoni, GIRARD, Proc. Ac. Nat. Sci. Phila., 1854, 133, Williamson Pass,* Cali- 

 fornia; (Coll. Lieut. Williamson); GIRARD, Pacific R. R. Surv., x, 93, 1858; SAUVAGE, Revi- 

 sion des fipinoches, 25, 1874; ROSA SMITH, Proc. U. S. Nat. Mus., 1883, 217; f EIGENMANN, 

 I. c., 247. 



*This pass is not recognized on the maps, but it is near the present village of Saugus, Ven- 

 tura County, California. 

 f Specimen said to have come from an artesian well at San Bernardino, California. 



