PATELLA. 



261 



Explanation of the Plates. 



Beference Letters used in the Plates. 



Note. — The letters d — n in Figs. 136 and 13c refer to the minute 

 muscles of the odontophore, and are not included here. 



A. — Thin brown external layer 



of shell. 



A.C. = Anterior cartilage of 

 odontophore. 



A.-D. Lobe — Antero-dorsal lobe 

 of right kidney. 



A.-L.C. = Antero-lateral car- 

 tilage of odontophore. 



An. C. — Anal cells. 



Ant. Ao. = Anterior aorta. 



Ap. D. — Apical disc. 



B. = Thick middle layer of shell. 



(a) Outer part traversed by 



branching canals. 



(b) Clear inner part. 

 B.C. = Buccal cavity. 

 Bp. = Blastopore 



Buc. — Buccal commissure. 

 Buc.D. = Duct of buccal gland. 

 Buc.G. = Buccal ganglion. 

 Buc.Gl. = Buccal glands. 



C. = Internal laminated layer of 



shell. 

 Ccr. — Cerebral ganglion. 

 Cer.C. — Cerebral commissure. 

 Cil.B. = Pre-blastoporal ciliated 



ring which becomes proto- 



troch. 



C.-Ped. — Cerebro-pedal con- 

 nective. 



C.-Pl. = Cerebro-pleural con- 

 nective. 



D.F.G. = Dorsal fold of gullet 

 wall. 



D.H.P. = Duct of hepato- 

 pancreas. 



D.P. = Dorsal palatal plate. 



D.Pal.Gl. — Dorsal pallial gland- 

 tissue. 



Ect. = Ectoderm. 



E.-M. — Endo-mesoderm. 



Ep. F. =* Epithelial fold. 



El. = Flap of lateral (" epipo- 

 dial ") streak. 



F.R. = Foot rudiments (meso- 

 blastic). 



G.-l. — Gland tubules of lateral 

 (" epipodial ") streak. 



G.M.T. = Greater pallial ten- 

 tacle. 



G.M.V. = Great pallial vein. 



Go. = Gonad. 



G.V. = Veinlet from pallial 

 gill. 



//. - Head. 



H.-P. — Hepato-pancreas. 



