Abstract
SYNOPSIS. A species of Nosema parasitizing the skeletal musculature of the crab, Callinectes sapidzrs Rathbun in the Patuxent River and Chesapake Bay, Maryland, is reported. Spores, in life, are ovoid and measure 2.2 μ by 1.7 μ When stained they are about 1.7 μ by 1.2 μ They closely resemble those of N. pulvis Pérez. 1905, in the muscles of Carcinides maenas (L.) but may he slightly larger Lysis of muscle fibers acoompanying heavy infection was noted, but the impontance of the parasite as a mortality factor in crabs is unknown.