122 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4rH SER. 
MEASUREMENTS (in millimeters) 
Upper Mandible Middle 
No. Sex | Length | Extent | Wing | Tail | Culmen|————————_ Tarsus | Toe and 
Depth | Width Claw 
8l1l |] o 345 COA area 74 33 8.4 | 12.2 | 42.9 | 49.1 
DIOR T AW eerie 224 | 79 32 8 12.6 | 42.4 | 47.9 
Poles SUH roel Pane eee 8 hoa lane ale 222 | 77.8) 31.9 8 12 43 48.8 
BOSS ae alin ee 236 | 77 35 8.3 |. 12.9 | 46 50.1 
810 | 9 368 775 | 242 | 77 33.4 8 11.1 | 43.5 | 49.1 
Ep WAN FOC OH) Keen ely eI aCe HEE 15 31.2 7 12.2 | 41.2 | 46.4 
813 | 2 363 Nee ke 238 | 81 32.4 7.8 | 11.9 | 40.7 | 46.8 
ZIAD SOE Om ae ee A ioral 226 | 78 31 8 12.3 | 42.6 | 48.5 
DAO SO Oe ire ea al entice 230 | 78 31 8 12.5 | 43.5 | 49.2 
PAN MS Yeh ES MISCO Ee gone ane 239 | 80 35 8 12 44.9 | 50 
PA MSY, BB Roe a Lau eres] bear 230 | 76 by) 51 7.5 | 11.5 | 44 49.5 
ORAL EE ato eral Dea eset Deh 228 | 71 32 8 12 43.2 } 48.1 
ZO AG Oe slice ails 229 | 79 31.2 7.6 | 11.5 | 44 48 .2 
219484 9 f..... cd... ee. 227 | 78 32 8.4} 12.5 | 44.4] 49.8 
PVOSO MON ets Mees ieee an 224 | 79 30.9 7.8 | 12.1 | 41.2 | 46.2 
TUT SAO A MON ee al eel 229 | 80 30 7.5 | 12.3 | 43.5 | 48.5 
PLOO ieee Goer als ae 240 | 80 33.8 9 13.7 | 46.5 | 51.6 
CORSA isa Ol et eee ahh 221 | 77 33 8 12.5 | 46 47 
Puffinus obscurus (Gmelin): Dusky SHEARWATER; LEAST 
SHEARWATER 
Coves—Puffinus obscurus, II, 137, 144; Puffinus nugax, II, 141, 144; 
[Puffinus] assimilis, V, 192. 
SALvIN—Puffinus obscurus, 369, 382; Puffinus assimilis, 370, 384; Puf- 
finus persicus, 369, 381, pl. 4; (?) Puffinus elegans, 370, 385. 
GopMAN—Puffinus obscurus, vi, xiii, 126, pl. 34; Puffinus subalaris, xli, 
117; Puffinus auduboni, xiii, 129; Puffinus assimilis, xiii, 133, pl. 35; 
Puffinus bailioni, xlii, 138; Puffinus persicus, xlii, 124, pl. 33; (?) 
Puftinus elegans, xiii, 136, pl. 36. 
Following Lord Rothschild and Dr. Hartert,° I have 
grouped under Puffinus obscurus several book species, believ- 
ing them to be merely variations of a single widely distrib- 
uted and essentially non-migratory species. The material 
before me confirms that the intergradation is complete be- 
tween the brownish-backed and bluish-backed birds and that 
they are not separable as distinct species. Perhaps the ex- 
planation of the dual coloration is to be found in dichroma- 
tism, more or less modified by geographic variation. Puffinus 
persicus Hume has been included in the synonymy, as it is 
1 Carnegie Museum. 
2 Type of Puffinus auricularis; U. S. National Museum. 
3“<Puffinus newelli;’ Bishop Museum. 
* Type of “Puffinus newelli;’ Bishop Museum. 
5 Nov. Zool., v. 6, pp. 194-197. 
