140 CALIFORNIA ACADEMY OF SCIENCES __ [Proc. 4t# Sr. 
taken in the flesh. The most tangible characters separating the 
two species are the form and dimensions of the bill. The bill 
of P. tenuirostris is shorter than that of P. griseus; it is also 
weaker at the tip and relatively, sometimes actually, wider at 
the base. The culmen in forty-four specimens measures 29./— 
35 mm., while in one hundred and sixty-five specimens of P. 
griseus it measures 38.3—47.3 mm. P. tenuirostris is further 
distinguished, in the dark phase, by the uniformity of the gray 
of the under coverts of the wing, the shaft stripes and other 
heavy dark markings often present on these coverts in P. 
eriseus being altogether wanting. In the extreme light phase 
of both species the under coverts of the wing are white, and 
therefore not diagnostic. 
Mr. Ridgway’s analytical key to P. tenwirostris* is not 
always adequate; the exposed culmen in short-footed examples 
(notably No. 9758 C. A. S.) is sometimes decidedly longer 
than the combined length of the first two divisions of the outer 
toe. The keys of Mr. Salvin and Dr. Godman are still more 
inadequate, the length of the wing” and absence of white on the 
under wing-coverts® being given as differential characters of 
the species. 
Appended are the dimensions in millimeters of twenty-two 
males and twenty-two females—all from the ocean in the vicin- 
ity of Point Pinos, California. 
Upper Mandible Middle 
Sex | Wing | Tail |Culmen|— | ____ | Tarsus |Toe and 
Depth | Width Claw 
Maximum ES ARCS an Ea ae o' | 290 90 |} 35 9.6 | 16 51 63.5 
Minimum........... o | 266 81 | 31.7 8 14 46 58 
Meaning xen neice: o | 282 85 | 33.3 8.8 | 14.7 | 48.2 | 60.9 
Maximum AE OOS Or aay 12) 286 87 | 35 9.5 | 15.1 | 50.3 | 62.3 
Minimum........... @ | 264 77 :*| 29.7 8 13.2 | 44.3 | 56.1 
Mica stream saen a ununen Q | 274 84 | 33 8.7 | 14.4 | 48.2 | 59.5 
The above measurements show a slight difference in the size 
of the sexes in favor of the males. 
1 Man. N. A. Birds, p. 62. 
2 Salvin, monograph, p. 370. 
3 Mon. Petrels, p. xiii. 
