 Together, they introduced Darwinian concepts into secondary education and began their studies on the taxonomy and behavior of jumping spiders (Salticidae), a large group of visually oriented spiders.They were among the earliest taxonomists to emphasize the value of behavior in classification.In 1889-1890 they published "Observations on Sexual Selection in Spiders of the Family" Attidae, and "Additional Observations on Sexual Selection in Spiders of the Family" Attidæ," with Some Remarks on Mr. Wallace's Theory of Sexual Ornamentation", among the first studies on sexual selection, supporting Darwin's concept against Wallace's alternative explanation of courtship behavior.