41 



DESCEIPTION OF THE PLATES. 



List of Eefer 



amb. ep. — Ambulacral epithe- 

 lium. 



amh. gr. = Ambulacral groove. 



awh. nv. — Ambulacral nerve. 



an. = Anus. 



an. fl. = Anal funnel. 



arc. = Archenteron. 



ax. en. = Axial canal. 



ax. or. = Axial organ. 



ax. si. = Axial sinus. 



has. = Basal plate. 



bl. Ic. = Blood lacuna. 



br. nv. c. = Brachial nerve cord. 



cal. d. = Cahciform cell. 



cen. cap. = Central capsule. 



chi. = Chiasma of radial cords. 



ch. or. = Chambered organ. 



ci. = Cirrus. 



ci. cd. — Cirrus cord. 



cil. pi. = Ciliated pit. 



ci. V. = Cirrus vessel. 



d. fn. = Cihated funnels. 



d. r. = Cihated ring. 



cnt. dr. — Cen tro -dorsal plate. 



en. ts. — Connective tissue. 



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

 vessel. 



coe. ca. = Coeliac canal. 



COS. en. = Coelomic endothehum. 



cog. — Coagulum. 



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

 ficial nerve ring. 



c. 0. w. V. = Circum-oral water 



vessel. 

 ct. = Cuticle. 

 cv. p. = Covering plate. 



d. 0. nv. = Nerves of deeper oral 



system. 



ExcE Letters. 



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 Ugaments. 

 fix. m. = Flexor muscles. 

 gen. bl. Ic. = Genital blood lacuna. 

 gen. ra. = Genital rachis. 

 hyd. = Hydroccel. 

 hyd. r. = Hydroccel ring. 

 hyp. = Hydropore. 

 i. m. /. = Isolated muscular fibres. 

 int. = Intestine. 

 int. ep. = Intestinal epithelium. 

 int. lig. = Interarticular hga- 



ments. 

 jt. pn. — Calcareous joint of 



pinnule. 

 jt. sk. — Calcareous stalk joint. 

 I. COS. — Left ccelom. 

 /. m. f. = Longitudinal muscular 



fibres. 

 It. nv. c. = Lateral cord of deeper 



oral nervous system. 

 me. hy. vs. = Mesentero -hydroccel 



vesicle. 

 mes. = Mesenchyme. 

 mth. = Mouth. 

 nv. I. = Nerve layer. 

 or. = Oral plate. 

 or. pn. — Oral pinnule. 



