sea-fisheries laboratory. 

 Description of Plates. 



309 



Reference Letters. 



A. U.S. = Achsetous body seg- 

 ment. 



Ac. = Aciculum. 



Act. = Acrosome or apical body 

 of spermatozoon. 



An. = Anus. 



Ant.L. = Anterior lobe of brain. 



Au. = " Auricle." 



B. = Blastophore (residual mass 

 of protoplasm). 



Bl. V. = Blood vessel. 



Br. = Gill. 



Br.Aff. \ = Afferent and efferent 



Br.Eff. ) branchial vessels. 



Br. and N.Aff. = Afferent vessel 

 to gill and nephridium. 



B.SJi. = Sheath formed of buccal 

 muscles. 



Bucc.M. = Buccal mass. 



Bucc.Pap. = Papilla; of buccal 

 mass. 



Caud.Sep. = Caudal septum. 



Ch.Seg.= Chgetigerous segment. 



Chl.Gr. = Chlorogogen granules. 



Chl.Tiss. = Chlorogogenous tissue. 



Cod. = Coelom. 



Ccel.Epith. = Ccelomic epithelium. 



Conn.Tiss. = Connective tissue. 



Cut. = Cuticle. 



Diat. = Diatom (as otolith). 



D.L.V. = Dorsal longitudinal 

 vessel. 



D.Mes. = Dorsal mesentery. 



Dphm. = Diaphragm. 



Dphm.P. = Pouch of first dia- 

 phragm. 



D.V. = Dorsal vessel. 



Endth.N. = Nucleus of endo- 

 thelium. 



Ep. = Epidermis. 



Exc.Gr. = Excretory granules. 



Ext.Op.Ot. = External opening 

 of otocyst. 



Gang.C. = Ganglion cell. 



Gast.Lat. = Lateral gastric 

 vessel. 



G.C. = Giant nerve cell. 



G.F. = Giant nerve fibre. 



Gl.C. = Gland cell. 



Gon. = Gonad. 



Gon.V. = Gonidial vessel. 



Ht.B. = Heart body. 



Int.V. = Intestinal vessel. 



M.Circ. = Circular muscles. 



Met.Gr. = Metastomial groove. 



Mid. Com. = Middle commissure 

 of brain. 



21. Long. = Longitudinal muscles. 



Mo. = Mouth. 



M.Obl. = Oblique muscles. 



M.P. = Middle piece of sperma- 

 tozoon. 



Muse. = Muscles. 



iV. = Nucleus. 



N.Aff. = Nephridial afferent 

 vessel. 



N.C. = Nerve cord. 



N.Ep>. = Nerve to epidermis. 



Nfb. = Neurofibrillse. 



Ngl. = Neuroglia. 



Nlm. = Neurilemma. 



N.L.V. =Nephridal longitudinal 

 vessel. 



Nm. = Neuropodium. 



