THE HABITS AND STRUCTURE OF ARENICOLA MARINA. 119 



EXPLANATION OF PLATES VI.— X. 



Illustrating Mr. F. W. Gamble's and Mr. J. H. Ashworth's paper on " The 

 Habits and Structure of Arenicola marina." 



List of Reference Letters. 



A. Cr. Anterior cornua of the brain. An. Anus. Au. "Auricle" of the 

 heart. Bl. Bladder or terminal part of the nephridia. Blph. Blastophore of 

 spermatoblast. B. Pap. Papilla? of the buccal mass. Br. Gills. Br. Aff 

 Branchial afferent vessels. Br. Eff. Branchial efferent vessels. BE. Brain 

 B. S. Blood spaces in the heart. B. Sh. Sheath of retractor muscle enclosing 

 the buccal mass. Bucc. M. Buccal mass. Card. B. Cardiac body. Chi, 

 Tiss. Chlorogogenous tissue on the stomach and ventral vessel. Chn. Noto 

 podial chsetse. C. F. Cardiac fibres. C. Sp. Caudal septa. D. L. V. Dorsal 

 longitudinal vessel. D. Np>h. Dorsal lip of the nephrostome. Dph. Ph 

 Diaphragmatic pouch. Dphm. : - 3 > Diaphragms or anterior septa. Ep 

 Epidermis. G. Refringent granules in ccelomic cells. Ga. Ganglion-cells of 

 the brain. Gast. Lat. Lateral gastric vessel. Gast. V. Gastric vessels. 

 G. F. " Giant fibres." Gl. Op Opening of the oesophageal glands into the 

 oesophagus. G. S. Granular cells of the heart. G v. Ventral groove of 

 alimentary canal. G. V. Gonidial vessel. Int. V. Intestinal vessels. M. 

 " Middle piece " of spermatozoon. M. Circ. Circular muscles. Mes. D. and 

 Mes. V. Mesenteries supporting the dorsal and ventral vessels between the 

 first and second diaphragms. MET. t: Metastomium," or achsetous portion 

 of the body immediately following the prostomium. M. Long. Longitudinal 

 muscles. MO. Mouth. M. Ob. Oblique muscles. M. Par. Parapodial 

 muscles. M, Pr. Retractors of the prostomium. N. Nucleus. N. Aff. 

 Afferent vessel to the nephridia. N. C. Ventral nerve-cord. N. Cap. 

 Nephridia! capillaries. N. Eff. Efferent vessel from the nephridia. NLV. 

 Nephridial longitudinal vessel. Nm. 1_1 °- Neuropodia. No. 1_ 6 - Nephridio- 

 pores. NPH. 1 ~ 6 - Nephridia. NPHM. Nephrostomes. NS. Nervous elements 

 and connective tissue round otocyst. Nu. Nuchal organ. Nu. Tr. Retractor 

 muscle of nuchal organ. N. V. Neural vessels. Oe. Oesophagus. Oe. Comm. 

 Circum oesophageal nerve-connectives. Oe. Gl. Oesophageal glands. Oe. Gl. V. 

 Vessel of oesophageal glands. Oe. Lat. Lateral oesophageal vessel. 0. Ot. 

 External opening of otocyst. OT. Otocysts. OT 1 . Neck of otocyst. Oth. 

 Otolith. OT. N. Nerve to otocyst. Par. V. Parietal vessels. P. Cr. Posterior 

 cornua of brain. Pn. Protractor of notopodium. Pr. Prostomial lobes. 

 Rn. Retractor of notopodium. S. Cap of spermatozoon. S. V. Sub- 

 intestinal vessels. T. Tail of spermatozoon. V. Ventricle of the heart. 

 Vac. Vacuole. Vac. C. Vacuolated cells of the heart. V. Ni)h. Ventral lip 

 of nephrostome. V. V. Ventral vessel. /. //. ///. IV. ifcc. Somites 

 beginning with the first chretigerous. 



