A still more remarkable resemblance exists in the shape and striking, red, black and yellow coloration between Scolecophis aemulus of Chihuahua and the poisonous Elaps fulvius, the American coral-snake, but Cope has been careful to point out that these two creatures are not known to inhabit the same district.
The coloration of tsetse-flies is sombre and inconspicuous; the brownish or greyish-brown thorax usually exhibits darker longitudinal markings, and when the insect is at rest the abdomen or hinder half of the body is entirely concealed by the brownish wings.
Hence as a very general rule the coloration makes for concealment under natural conditions of existence, and the instincts which lead to concealment are very highly developed.
Detection and Estimation.-Most calcium compounds, especially when moistened with hydrochloric acid, impart an orange-red colour to a Bunsen flame, which when viewed through green glass appears to be finch-green; this distinguishes it in the presence of strontium, whose crimson coloration is apt to mask the orange-red calcium flame (when viewed through green glass the strontium flame appears to be a very faint yellow).
The same style of coloration is found in Coleoptera of the families Cetoniidae and Cantharidae; in Diptera of the families Asilidae, Bombylidae, Tabanidae and Tachinidae; in Hemiptera of the family Reduviidae and in Lepidoptera of the family Zygaenidae.
It crystallizes in dark red prisms which are readily soluble in water; it is a valuable reagent for the detection of sulphur, this element when in the form of an alkaline sulphide giving a characteristic purple blue coloration with the nitroprusside.
The young are prettily spotted with white and black ocelli, but the coloration of the adult is mostly very plain.
C. antiquorum, are characterized by the large frontal horn of the bulls, the white legs, the network type of coloration and the pale tint.
Compounds of copper impart a bright green coloration to the flame of a Bunsen burner.
Sulphur is detected by heating the substance with sodium, dissolving the product in water, and adding sodium nitroprusside; a bluish-violet coloration indicates sulphur (H.