Hood depressors of Phoronopsis harmeri larva. A. Fine morphology of hood depressor (closed arrowheads), which passes along the wall of the collar to the circular ring muscle (cr). B. Semi-thin cross section of the central part of the preoral lobe and preoral coelom (c1) with upper portion of hood depressors (hd). C, D. Cross sections of the preoral lobe. C. Singular branch of the hood depressor is surrounded by thin projections of coelothelial cell (open arrowheads). D. Hood depressor muscle bunches (blue) are integrated between the coelothelial cells of preoral coelom (c1) lining. Abbreviations: bc – blastocoel; tc – transverse muscles of the collar.