ALPHABETICAL EXPLANATION 



Of the Meaning of the Letters in Plates X. and XI. 



a, anus 



w a , spinal marrow 



aw, eye 



ma, anterior opening of the medal 



6, ventral muscles 



lary tube 



c, gill-cavity 



mb, muscular ligaments 



ch, notochord (spinal axis) 



mg, stomach 



cl, cloacal cavity 



mh, mouth-cavity 



cs, notochord sheath 



mp, muscle -plate 



d, intestinal tube 



mt, mantle 



do, dorsal wall of the intestine 



n, nose (nose-pit) 



du, ventral „ „ „ 



o, mouth-opening 



e, ovary 



p, ventral pore 



en, endostyle 



q, cloacal opening 



/, fin-seam 



r, dorsal muscles 



g, ear-vesicle 



«, tail-fins 



h, horn-plate 



si, seed-duct 



hd % testes 



sm, opening of the seed-duct 



hk, venticle 



ss, organ of sense 



hv, auricle 



t, aorta (dorsal blood-vessel) 



hz, heart 



th, thyroid gland 



»» eggs 



u, side canals 



k, gills 



v, intestinal vein (ventral blood. 



lea, gill-artery 



vessel) 



I, leather-plat© 



w, root -fibres of the ascidian. 



lb, liver 



<B, boundary between the gill.intes- 



W, anterior end of the liver 



tine and the stomach-intestine 



b), liver vein 



y, hypo-branchial groove 



m, medullary tube 



0, embryos of the ascidian 



*»., brain-bladder 





