* The Striking Likeness: Holmes recognized a strong resemblance between the portrait of Hugo Baskerville and Sir Charles Baskerville, the recent victim. This was significant because the Baskervilles were known for their remarkable family resemblance, and the likeness suggested a possible link between the two men.
* The Expression of Terror: The portrait depicted Hugo Baskerville with an expression of extreme terror, staring directly at the viewer. This added to the unsettling atmosphere surrounding the Baskerville family and hinted at a possible connection to the mysterious hound.
* The History of the Baskervilles: The portrait was a tangible link to the Baskerville family's history and their legendary connection to the hound. Holmes used the portrait as a starting point to research the family's past and uncover any potential secrets or connections to the events surrounding Sir Charles' death.
Overall, the portrait of Hugo Baskerville served as a key piece of evidence for Holmes, providing him with a crucial visual link to the Baskerville family, their history, and the chilling legend of the hound.