DEVELOPMENT OF BALANOGLOSSUS KOWALEVSKII. 529 
EXPLANATION OF PLATES XXVIII, XXIX, XXX, 
XXXII, XXXII ann XXXIII. 
Fies. 64—112, 
Illustrating Mr. Bateson’s Paper on “ The Morphology of the 
_ Enteropneusta.” 
Complete List of Reference Letters. 
a. Anus. al. Alimentary canal. a¢. Atrial cavity. dc. 1, 2, 3. The anterior, 
middle, and posterior body cavities respectively. 4g. Rods bordering the gill- 
slits. dr. c/s. Border cells of proboscis gland (B. salmo news}—\b. v. Blood- 
vessel. C. WV.S. Central nervous system (¢.e. the cord of the collar region). 
Cap. Capillaries of proboscis gland. Circ. Circular muscle-fibre. C/.,f. Collar 
funnel. C.rg. Ring of nervous tissue round the collar. D. d.v. Dorsal 
blood-vessel. D. mes. Dorsal mesentery. 2D... s. Dorsal nervous cord. 
D.r. Cords connecting central nervous system with the skin. D. rdg. Dorsal 
ridge of hypoblast in branchial region. diy. Digestive region of alimentary 
canal. #. Ectoderm. ff. Fold in wall of collar funnels. gy. s. Gill-slit. 
g. 5-1, *. First and second gill-slits respectively. . g. sc. Lining of gill-sac. 
g. sr. Supporting rods of gills. g. vs. Germinal vesicle. y. sp. Germinal spot. 
gl. Proboscis gland. gl. s. Sac of proboscis gland. gud. Granules in central 
nervous system of B. salmoneus. gr. Granules, probably excretory. 
At. Heart. int. Intestine. 1. d. v. Lateral blood-vessel. 7. rdg. Lateral 
ridges separating the branchial chamber from the lower cavity of the gut in 
the branchial region. /. msc. Longitudinal muscle-fibres. Zv. Liver. m. spz. 
Spermatoblast cells. Mo. Mouth. msc. Muscle-fibres. mz. Mucous glands of 
skin. mu’. Goblet cells of skin. mz'’. Long glands of collar skin of B. 
Kowalevskii. 2. cv/. Neural canal. Neh. Notochord. J. pr. Neural 
pore. . sh. Nervous sheath of proboscis. 0. Opening of collar pores. 
Op. Operculum. ov.? Ingrowth of skin, probably an ovary. ov. Ovarian 
follicle. pA. Pharyngeal region of gut with thick walls. er. Perforation 
into liver saccule. pét. Fibrous substance of the nervous system. P. rg. 
Ring of nervous tissue round proboscis. ph. c. Perihemal body cavity. 
Scl. Liver saccule. Sf Surface of skin with anastomoses of ectoderm cells. 
Sk. Skin. Skr. Sucker. §. 7. Supporting rod of notochord. Sp. viv. Spiral 
fold in wall of gut in the digestive region. S?. Stripes occasionally seen in 
preserved muscle-fibres.  Sve/. Stellate masses of cells in central nervous 
system. ¢. pr. Tube of proboscis pore. ¢s. Testis. V. dd. Ventral band of 
longitudinal muscle of B. Kowalevskii. V. 6. v. Ventral blood-vessel. 
