EXPLANATION OF PLATES 46 — 53. liii 



EXPLANATION OF PLATES 46— =,31. (XXV. p. 871.) 



Complete List of Reference Letters. 



A. Anus. a. Dorso-lateral horn of white matter in brain, a.g. Accessory gland 

 of male (modified accessory leg gland), at. Antenna, al. n. Antennary nerve, b. 

 Ventro-lateral horn of white matter of brain, b. c. Body-cavity. 61. Blastopore. 

 c. Cutis, c. Postero-dorsal lobe of white matter of brain. e.g. Supraoesophageal 

 ganglia, cl. Claw. c. m. Circular layer of muscles, co. Commisiures between the 

 ventral nerve-cords. C0.2. Second commissure between the ventral nerve-cords. 

 co^. 2. Mass of cells developed on second commissure, cor. Cornea, c. s. d. Com- 

 mon duct for the two salivary glands, cii. Cuticle, d. Ventral protuberance of 

 brain. d.l.m. Dorsal longitudinal muscle of pharynx, d.n. Median dorsal nerve 

 to integument firom supraoesophageal ganglia, d. 0. Muscular bands passing from the 

 ventro-lateral wall of the pharynx at the region of its opening into the buccal cavity. 

 E. Eye. E. Central lobe of white matter of brain, c.n. Nerves passing outwards from 

 the ventral cords, ep. Epidermis, ep.c. Epidemiis cells. F. i,F. 2, d-r. First and 

 second pair of feet, &c. f. Small accessory glandular tubes of the male generative 

 ■ apparatus. F.^. Ganglionic enlargement on ventral nerve-cord, from which a pair of 

 nerves to foot pass off. /. gl. Accessory foot-gland. F. n. Nerves to feet. g. co. 

 Commissures between the ventral nerve-cords containing ganglion cells, g. 0. Gene- 

 rative orifice. H. Heart, h. Cells In lateral division of body-cavity, hy. Hypo- 

 blast, i.j. Inner jaw. j. Jaw. j.n. Nerves to jaws. L. Lips. /. Lens, l.b.c. 

 Lateral compartment of body-cavity. /■.•. Jaw lever (cuticular prolongation of inner 

 jaw lying in a backwardly projecting diverticulum of the buccal cavity). /. m. Bands 

 of longitudinal muscles. M. Buccal cavity, m'. Median backward diverticulum of 

 mouth or common salivary duct which receives the salivary ducts, itie. Mesenteron. 

 mcs. Mesoblastic somite, in. I. Muscles of jaw lever, m. s. Sheets of muscle passing 

 round the side walls of pharynx to dorsal body wall. od. Oviduct, cc. CEsophagus. 

 CCS. CO. CEsophageal commissures, o.f. g. Orifice of duct of foot -gland. o.J. Outer 

 jaw. op. Optic ganglion, op. it. Optic nerve, or.g. Ganglionic enlargements for 

 oral papilla:, or.n. Nerves to oral papillae, or. p. Oral papillae, o.s. Orifice of 

 duct of segmental organ. oz<. Ovary, p. Pads on ventral side of foot. p. Common 

 duct into which the vasa deferentia open. /. c. Posterior lobe of brain. /. d. c. 

 Posterior commissure passing dorsal to rectum, p./. Internal opening of nephridium 

 into body cavity. pA. Pharynx, pi. Pigment in outer ends of epidermic cells, pi. 

 Retinal pigment, p. n. Nerves to feet. p.p. Primary papilla, pr. Prostate. 

 Rectum. Jfc. Retinal rods. R.iii. Muscle of claw. s. Vesicle of nephridium. 

 Part of 4th or 5th nephridium which corresponds to vesicle of other nephridia 

 s. c. I. Region No. i of coiled tube of nephridium. s.c.i. Region No. 2 of ditto 

 s. c. 3. Region No. 3 of ditto. s. c. 4. Region No. 4 of ditto, s. d. Salivary duct 

 s.j;. Salivary gland, s/.d. Reservoir of slime gland, si.g. Tubules of slime gland 

 s.o. I, 2, 3, >S~Y. Nephridia of ist, and, &c., feet. s. o.f. Terminal portion of nephri- 

 dium. s.p. Secondary papilla, st. Stomach, st.e. Epithelium of stomach. 

 Sympathetic ner\'e running in muscles of tongue and pharynx, j^'. Origin of pharyn. 



^ The explanations of the figures printed wthin inverted commas are by Professor Balfour, 

 the rest are by the Editors. 



