50 i ALFRED GIBBS BOURNE. 



wall of a sinus. One cell may be seen recently divided, a. Connec- 

 tive-tissue layer. 

 (Figs. 44—47 occur on Plate XXXIV.) 

 Fig. 44. — Pontobdella. A "lymphatic nodule." m. n. Blood-vessels. 

 0. The connective - tissue capsule. p. The trabecular network. 

 q. Enclosed amoeboid corpuscles. The majority of these corpuscles 

 have been omitted to show the trabecular network. 

 Fig. 45. — Pontobdella. Portion of the dorsal sinus and vessel. 

 d. s. Dorsal sinus, m. Muscular band in its wall. d. v. Dorsal vessel 

 lying in the sinus. The scattered nuclei in the walls are shown. 

 Fig. 46. — Pontobdella. Portion of the lateral sinus and contained 

 vessel. I. s. Lateral sinus, with au almost obliterated lumen, m. Mus- 

 cular band in its wall. I. v. Lateral vessel with its densely-muscular 

 walls. 

 Fig. 47. — Pontobdella. a. Capillary vessel, c. The cuticle of the 

 walls, p. The protoplasmic lining, with nuclei d. a. Amoeboid cor- 

 puscles running here and there into plasmodial masses. 

 Fig. 48. — Hirudo. Cells from the apical lobe of the nephridium. d. 

 Duct. a. Nuclei in its walls. Perforated cells, c. c, are indicated in the 

 drawing on each side of this main duct. 6. b. Their nuclei, duct. Their 

 ductules, caji. Blood capillaries. 

 Figs. 49—58 occur on Plate XXXI. 



Fig, 49. — Hirudo. "Funnel" of the nephridium. a. The many-lobed 

 mass surrounding the dilated portion and constituting the " funnel." b. The 

 extremity of the " testis " lobe. 



Fig. 50 a, b, c. — Hirudo. Various ciliated cells from the surface of the 

 funnel. These do not exhibit any actual apertures, but are of a spongy nature, 

 and in some cases present an intracellular lumen, I. n. Nuclei, m. Connec- 

 tive tissue upon which they lie. 



Fig. 51. — Trocheta. Botryoidal sinus containing the funnel of the ne- 

 phridium, seen in transverse section, c. t. Connective tissue forming a 

 capsule, m. Small muscular fibres developed in the walls. ep. Cells of 

 botryoidal tissue forming an epithelium, t. Communication with the blood 

 system, neph. Nephridial cell. r. Diverticulum following on the mouth of 

 the funnel,/!, containing degenerating blood corpuscles, coel. Ccelomic space. 

 Tlie actual communication between the nephridial cell and the dilated neck of 

 the funnel is not shown. 



Fig. 52. — Clepsine. Ventral sinus with nephridial funnels, from trans- 

 verse sections. Diagrammatic, v. s. Ventral sinus, v. v. Ventral vessel. 

 n. g. Nerve-ganglion, giving off lateral branches, f.f. Funnels of the ne- 

 phridia. v. Diverticulum following upon the mouth of the funnel, filled as in 

 Fig. 51. neph. Nephridial cells. 



Figs. 53 and 54. — Pontobdella. Funnel and diverticulum of the nephri- 



