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 116 TH CONDOR Vol. XVIII length, and finally joined in two graceful curves, leaving a small pool in the V-shaped depression between them. The sand along the beach and spit is almost entirely o51itie in structure and hence lends itself exceptionally well to the rolling action of the waves. The crown part of Hat Island is composed of a hard, almost black, conglomerate. There was little vegetation to be found on the island and this composed of very few species. The only plants observed were one species of allium or wild leek, one erueiferous species resembling the shepherd's purse, one species of the borage family, one ehenopodium, one species of cactus, alfileria, and one of the greasewoods. The last was somewhat plentiful while the others were merely sporadic. The fauna on this island was likewise extremely limited in number of species. In addition to a few insects, we found only one species of lizard and six species of birds. The latter, in the order of their relative Fig. 36. CALIFORNIA AND RING-BILLED GULLS ON I-IAT ISIND. THERE ARE 754 BIRDS IN- CLUDED IN THE PICTURE. abundance, were: the California Gull (larus californicus), the Ring-billed Gull (Larus delawarensis), the White Pelican ( Pelecaus erjthrorhychos), the Great Blue Heron (Ardea herodio tregazai), the Caspian Tern (terna copia), and Killdeer (Oxyechus vociferus). Of the last we saw but one indi- vidual, and that was probably there as a mere visitor. The other five species were all found nesting on the islancL It is impossible to give an accurate estimate of the bird population of the rookery on Hat Island, hence the following is intended to be merely approxi- mately correct. It is possibly correct within a ten per cent error. The Califor- nia and the Ring-billed gulls comprised a majority of the population. It is impossible to state with any degree of definiteness which of these two was the most numerous. However, from the examination of a large number of indi-- viduals, it seemed that the California Gull was in the majority. An idea of the gull contingent will be had from figure 36. This picture was taken on the