38 r. W. GAMBLE AND J. H. ASHWORTH. 



EXPLANATION OF PLATES 1—5, 



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. Or. Anterior cornua of the brain. An. Anus. An. "Auricle" of the 

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

 spermatoblast. B. Pap. Papillae of the buccal mass. Br. Gills. Br. Aff. 

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

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

 closing the buccal mass. Biicc. M. Buccal mass. Card. B. Cardiac body. 

 C/il. Tiss. Chlorogogenous tissue on the stomach and ventral vessel. Chu. 

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

 Dorsal longitudinal vessel. D. NpJi. Dorsal lip of the nephrostome. Dph. Ph. 

 Diaphragmatic pouch. Dphm. '"^' Diaphragms or anterior septa. Ep. Epi- 

 dermis. 6. Refringent granules in coelomic 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. Gv. Ventral groove of ali- 

 mentary canal. G. V. Gonidial vessel. I>iL 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. " Metastomium," or achsetous 

 portion of the body immediately following the prostomium. M. Long. Longi- 

 tudinal muscles. J/O. Mouth. 3/. 06. Oblique muscles, viy. P^/r. Parapodial 

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

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

 phiidial capillaries. N.Eff. Efferent vessel from the nephridia. NLV. Ne- 

 phridial longitudinal vessel. Nm. '^'''' Neuropodia. No. ^~^' Nephridiopores. 

 NPIi. '"*■ Nephridia. NPHM. Nephrostomes. NS. Nervous elements and 

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

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

 Circumoesophageal nerve-connectives. Oe. Gl. Esophageal glands. Oe. Gl. V. 

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

 External opening of otocyst. OT. Otocysts. 07". Neck of otocyst. Olh. 

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

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

 Un. Retractor of notopodium. S. Cap of spermatozoon. S. V, Sub- 

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



