The Nematoda possess an elongated and thread-like form.
In the winter coat the hair is long and pendent, elongated into a short beard on the sides of the lower jaw behind the chin; and it is also longer than elsewhere on the neck and the chest; at the base of the long hair is a thick growth of short and woolly under-fur.
General form dog-like, with the head elongated, the muzzle pointed, and the ears moderate, erect and triangular.
The head is elongated, with a slender muzzle and the mouth-opening small.
The coenosarc may consist of a single elongated tube or stolon, forming the stem or axis of the cormus on which, usually, the appendages are arranged in groups termed cormidia; or it may take the form of a compact mass of ramifying, anastomosing tubes, in which case the cormus as a whole has a compact form and cormidia are not distinguishable.