Report of first expedition to South America, 1913 . ^ five bristles on theside of the labium, indicating perhaps a varietal form, but as a gill lobe may some-times be present on one side and not on the other the two forms are not very dis-tinct. This was the most common form among the larvae obtained. Larva No. 2 Length 10 mm. The fans have from twenty-five to thirty rays. Antennaewith the second joint about four times as long as thick and half as long as the first;all three joints pale yellow. Mandibles with the large apical teeth black, the otherspale. Maxillary palpi black, not bristly, ape
Report of first expedition to South America, 1913 . ^ five bristles on theside of the labium, indicating perhaps a varietal form, but as a gill lobe may some-times be present on one side and not on the other the two forms are not very dis-tinct. This was the most common form among the larvae obtained. Larva No. 2 Length 10 mm. The fans have from twenty-five to thirty rays. Antennaewith the second joint about four times as long as thick and half as long as the first;all three joints pale yellow. Mandibles with the large apical teeth black, the otherspale. Maxillary palpi black, not bristly, apex pale. Labium (Fig. 7 Text) with. Fig. 7. —Simulium larva, No. 2. Labium. the dentate apical margin narrow; median tooth large, trifid as the adjacent smalltooth is advanced forward, next tooth very small, next larger, followed by a largelateral tooth which is shorter than the median one; along the side of the labium isa row of three bristles, the anterior one large, the other two growing successivelysmaller. The anal respiratory organs are not extended in any of the specimensand I have been unable either to evert or observe them in examples treated withpotash or peroxide, although the integument covering these organs is not destroyedby such treatment.
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