O. jocosus 6 May 9 2 mi. S Zucar de Matamoros, 4350ft., Puebla Photo: Roll 25 # 10 (?). An area of fairly rich desert vegetation with large candelabra cortii, large agaves, thorny trees in leaf a several species of broad-leafed tree. All in all similar to vegetation where we hunted yesterday. Wrens were silent for most part (4:30-5:30 P.M.). I collected a lone bird in trees adjacent to a closer field and then saw a pair fly from a huge candel- alabra cortus in the field to a stand of original vegetation, where I collected a ? with broad- patch. Size of corpus lutea enlarged evident in- dicate eggs were recently laid. Only calls heard today was gua, gua, gua - "cortus wren call". I saw one bird give this call from top most twig of a large tree (25 feet up). - We seem to have best luck in finding these wrens where the big cortii are present. OT taken today had a 1/2 inch ring of fat in the interclavicular region. I would judge that the presence of fairly, large thorny trees is essential part of habitat for this Wren. Even so in good, extensive areas of seemingly suitable habitat these birds are local in occurrence - usually one or two pairs in a small area than a long stretch of forest without wrens - and many seemingly perfect situations lack these wrens. A few Thryothorus pleurostictus occur in similar places with O. jocosus.