Wood-decay fungus fungi of certain types remove cellulose compounds from wood and hence the wood becomes brown colour. Brown rot in a dry, crumbly condition is sometimes incorrectly referred to as "dry rot" in general. The term "brown rot" replaced the general use of the term "dry rot", as wood must be damp to decay, although it may become dry later. Dry rot is a generic name for certain species of brown-rot fungi. Brown-rot fungi of particular economic importance include "Serpula lacrymans" (true dry rot), "Fibroporia vaillantii" (mine fungus), and "Coniophora puteana" (cellar fungus), which may attack timber in buildings. Other brown-rot
Serpula tidal fashion. In the central circulatory system, the blood moves anteriorly from the tip of the abdomen to the front of the thorax through a sinus enveloping the alimentary canal, and posteriorly through a ventral blood vessel. The ventral vessel and the sinus communicate with each other by segmentally arranged ring vessels, and by a dorsal vessel, a transverse vessel, and a pair of circumesophageal vessels situated at the anterior end of the thorax. The dorsal vessel in some of the larger serpulids, like "Serpula", possesses a valve and a muscular sphincter, probably to prevent backflow of blood from the