110 



EXPLANATION OF PLATES 

 Kefeeence Letters 



A. buc.= Buccal artery. 



A. c.= Anterior aorta. 



A. cut.' — Cutaneous artery. 



A. col. = Columella artery. 



A. g.= Gastric artery. 



A. go. = Gonad vessels. 



A. pall. = Pallial artery. 



A. ped. = Pedal artery. 



A. pen. = Penis artery. 



A. vis. — Visceral artery. 



Af. ct.= Afferent branchial vessel. 



An. — Anus. 



A o. = Aorta. 



Br. v. — Branchial vessels. 

 bucc — Buccal ganglia, 

 c. = Cerebral ganglion. 

 C. c. = Occlusor muscle. 

 C. cav. = Blood spaces in oeso- 

 phagus. 



C. p. = Cerebro pedal connective. 

 c. d. m. = Centro dorsal muscle. 

 c. gr. = Granular cells of renal 



lamella. 

 Caec. = Oesophageal caecum. 

 cae. w. — Connective tissue of caec. 



wall. 

 cart. = Cartilage. 



cer. com. = Cerebral commissure. 

 Col. mus. = Columella muscle. 

 Con. £. = Connect- tiss. gland of 



Leiblein. 

 Con. = Connective tissue. 

 Cor. — Cornea. 

 Ct. = Ctenidium. 

 ct. ax. = Ctenidial axis. 

 ct. con. = Connective tissue of gill 



leaflet. 



ct. e.' = Epithelium of gill leaflet. 

 ct. ep. — Ctenidial epithelium. 

 ct. gl. = Connect, tissue of ctenidial 

 axis. 



cl. mus. — Ctenidial muscles. 

 ct. n. — Ctenidial nerve. 



D. m. s. = Dorsal trans, muscle 

 sheet. 



D. pr. m. — Dorsal protractor 



muscles. 

 Dg." = Lobe of stomach. 

 Dg. c. " Dg. c. ' = Cells of digestive 



gland. 



Dg. con. = Connective tissue of 

 gland. 



Dg.d. = Opening of post, digestive 



gland duct. 

 Dg.d.' = Opening of ant. dig. gland 



duct. 



Dg. gl. = Digestive gland. 



Dg. gr. = Granules of gland cells. 



Dg. nuc. — Nucleus of gl. cell. 



Eff. ct. — Efferent branchial vessel. 



Fpot = Foot. 



Foil. ep. — Follicular epithelium. 



Gc. ep. = Germinal epithelium. 

 Gl. c. — Gland cells. 

 Go. = Gonad. 



l.r.r. = Dorsal retractor muscles. 

 L.t.b. — Lateral odontophoral 

 bands. 



Lam. pr. — Lamellae of secondary 

 system. 



Lam. v. = Vein of renal lamella. 

 Lens = Lens. 



Ling. con. = Connective tissue of 



odontophore. 

 Ln. g. = Gland of Leiblein. 



M. = Mouth. 



m.v.r. = Median ventral muscles. 

 mem. — Membranous wall of larva. 

 Mu. gl. — Mucous gland. 

 M us. circ. — Circular muscles. 

 Mus. col. — Transverse sections of 

 mus. fibres. 



N. ax. = Nerve of ctenidial axis. 

 w.o£. = Otocyst nerve. 

 neph. gl. — Nephridial gland. 

 Nuc. — Nucleus. 



Nuc. Int. C = Nuclei of instersti- 

 tial cells. 



0. cav. = Lumen of oesophagus. 

 oe. con. = Connective tissue with 



longitud. muscles. 

 oe. con.' = Connective tissue. 

 oes. = Oesophagus. 

 Op. = Operculum. 

 Op. w. = Optic nerve. 



