ANTEDON. 



411 



DESCRIPTION OF THE PLATES. 



List of Reference Letters. 



amb. ep. = Ambulacral epithe- 

 lium. 



amb. gr. = Ambulacral groove. 



amb. nv. = Ambulacral nerve. 



an. = Anus. 



an. ft. = Anal funnel. 



arc. = Archenteron. 



ax. en. = Axial canal. 



ax. or. = Axial organ. 



ax. si. = Axial sinus. 



bas. = Basal plate. 



bl. Ic. = Blood lacuna. 



br. nv. c. = Brachial nerve cord. 



col. cl. = Caliciform cell. 



cen. cap. = Central capsule. 



chi. = Chiasma of radial cords. 



ch. or. — Chambered organ. 



ci. = Cirrus. 



ci. cd. = Cirrus cord. 



cil. pt. = Ciliated pit. 



ci. v. = Cirrus vessel. 



cl. fn. = Ciliated funnels. 



cl. r. = Ciliated ring. 



cnt. dr. — Cen tro -dorsal plate. 



en. ts. = Connective tissue. 



c. o. bl. r. = Circum-oral blood 

 vessel. 



cos. ca. — Cceliac canal. 



cos. en. = Coelomic endothelium. 



cog. = Coagulum. 



c. o. nv. r. = Circum-oral super- 

 ficial nerve ring. 



c. o. w. v. = Circum-oral water 



vessel. 

 ct. = Cuticle. 

 cv. p. = Covering plate. 



d. o. nv. = Nerves of deeper oral 



system. 



d. o. nv. r. = Circum- oesophageal 

 deeper nerve ring. 



dr. nv. = Dorsal nerves from 

 brachial cord. 



d. r. pn. br. = Double root of 

 pinnular branch of brachial 

 cord. 



ect. = Ectoderm. 



ep. = Epithelium. 



ex. ch. or. = Extension of cham- 

 bered organ. 



ex. lig. = Extensor ligaments. 



fix. m. = Flexor muscles. 



gen. bl. Ic. — Genital blood lacuna. 



gen. ra. = Genital rachis. 



hyd. = Hydrocoel. 



hyd. r. = Hydroccel ring. 



hyp. = Hydropore. 



i. m. f. = Isolated muscular fibres. 



int. = Intestine. 



int. ep. — Intestinal epithelium. 



int. lig. = Interarticular liga- 

 ments. 



jt. pn. — Calcareous joint of 

 pinnule. 



jt. sk. = Calcareous stalk joint. 



I. cm. = Left ccelom. 



I. m. f. = Longitudinal muscular 

 fibres. 



It. nv. c. — Lateral cord of deeper 

 oral nervous system. 



me. hy. vs. = Mesentero -hydrocoel 

 vesicle. 



mes. = Mesenchyme. 



mth. = Mouth. 



nv. I. = Nerve layer. 



or. = Oral plate. 



or. pn. = Oral pinnule. 



