Sealyham Terrier breed standard illustration: Long, broad and powerful, without coarseness. It should, however, be in perfect balance with the body, joining neck smoothly. Length of head roughly three-quarters height at withers, or about an inch longer than neck. Breadth between ears a little less than one-half length of head. stop. Cheeks - Smoothly formed and flat, without heavy jowls. Jaws - Powerful and square. Nose - Black, with large nostrils. White, cherry or butterfly bad faults.