Cross-section through a worm near its tail end. Lumbriculus variegatus Cross-section through a worm near its tail end. Labels: E = dorsal epidermis (Note the absence of a muscle layer directly above dorsal blood vessel in the tail) M = muscle layer of body wall DBV = dorsal blood vessel IN = intestine L = lateral giant fiber within ventral nerve cord VNC = ventral nerve cord CC = coelomic cavity IN CC VBV VNC

Lumbriculus variegatus Cross-sections through worm’s ventral nerve cord Top panel shows section from anterior region. Bottom panel shows section from posterior region. Labels: L = lateral giant nerve fiber M = medial giant nerve fiber N = neuropil N N