ALPHABETICAL EXPLAXATION" 

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



a, anus 



au, uye 



bf ventral muscles 



c, gill cavity 



c/j, notochord (spinal axis) 

 cl, cloacal cavity 

 cs, notochord sheath 



d, intestinal tube 



do, dorsal wall of the intestine 

 du, ventral „ ,, „ 



e, ovary 

 endostylo 

 fin-seam 

 ear-vesicle 

 horn-plate 

 testes 



Ilk, venticlo 



hvy auricle 



hz, heart 



»» eggs 



fc, gills 



fea, gill-artery 



I, leather-plato 



Zb, liver 



Ih'y anterior end of the liver 



Iv, liver vein 



m, medullary tubo 



m^, brain-bladder 



en, 

 /. 



h, 

 hd, 



m.^, spinal marrow 



ma, anterior opening of the modul. 



lary tube 

 mh, muscular ligaments 

 mg, stomach 

 mh, mouth-cavity 

 nip, muscle-plate 

 mt, mantle 



nose (nose.pit) 



mouth-opening 



ventral pore 



cloacal opening 



dorsal muscles 



tail-fins 



seed-duct 

 am, opening of the seed-duct 

 ss, organ of sense 

 t, aorta (dorsal blood-vessel) 

 th, thyroid gland 

 u, side canals 



V, intestinal vein (ventral blood. 

 vessel) 



root-fibres of the ascidian. 



boundary between the gill.intes- 

 tine and the stomach.intestinc 

 y, hypo-branchial groove 

 s, embryos of the ascidian 



n, 



0, 



P> 



r, 

 s, 



8l, 



W, 



X. 



