What was the name of the dog from which the Jack Russell Terrier breed is derived?

The Jack Russell Terrier is a small terrier that has its origins in fox hunting in England. They originated from dogs bred and used by the Reverend John Russell in the early 19th century, from whom the breed takes its name. John "Jack" Russell (21 December 1795 – 28 April 1883), known as "The Sporting Parson", vicar of Swimbridge and rector of Black Torrington in North Devon, was an enthusiastic fox-hunter and dog breeder.

In 1819, during his last year of university at Exeter College, Oxford, Russell spotted a little white terrier with dark tan spots over her eyes, ears and at the tip of her tail, who was owned by a local milkman. Russell bought the dog, on the spot, and this animal, called "Trump", became the foundation of a line of fox hunting terriers that became known as Jack Russell Terriers. They were well-suited by the shortness and strength of their legs for digging and flushing out foxes which had "gone to earth" having been hunted over-ground by fox hounds. They had a tempered aggressiveness that would provide the necessary drive to pursue and bolt the fox, without resulting in physical harm to the quarry and effectively end the chase, which was considered ‘unsporting’.

Russell was a founding member of The Kennel Club. He did not show his own fox terriers on the conformation bench, saying that the difference between his dogs and the conformation dogs could be likened to the difference between wild and cultivated flowers.