96 H. M. WOODCOCK. 



attaclimeui (epillielial). I. Tongue of investing membrane. T. M. Trans- 

 verse muscles, vac. Vacuoles, v. s. Vascular strands, z. Special zone of 

 the nucleoplasm. 



PLATE 1. 



Mode of life and general appearance, "C^stobia" irregularis and 

 " C." niinchiuii. 



EiG. 1. — C. irregularis in tlie blood-vessel of Holotliuria forskali; 

 outline drawn alive, the details filled in after mounting and staining. (The 

 nuclei of the wall rather diagrammatic). Osmic, picro-carmine. x SO. 



Fig. 2. — Ditto, obtained free of the blood-vessel ; drawn alive. X 100. 



Fig. 3. — Ditto, younger stage. Mounted whole. Osmic, picro-carmiuc. 

 X 150. 



Fig. 4. — Portion of diverticulum of respiratory tree of Cucumaria pen- 

 tact es, showing seven C. minchinii in situ; viewed whole. (In two cases two 

 of the parasites overlap, but they are not actually in contact.) Flemniing, 

 para-carmine, x 80. 



Fig. 5. — Two young evagiuated couples of G. irregularis {n. is the 

 second nucleus beginning to be cut through, ep. epithelial sac in which the 

 parasite lies). (Aj Seen whole; corr. subl. + acetic, para-carinine X SO; 

 (B) in section; corr. subl. + acetic, irou-hsem. + orange, x 250. 



Fig. 6. — (A) Portion of body-wall of Cucumaria pentactes, showing 

 two C. minchinii attached, x 3. (B) The upper parasite of (a). X \2. 



Fig. 7. — Portions of the wall (a) of a large distributing vessel, and (b) of a 

 small cross-connection in H. forskali. Fron a section. Corr. subl. -f 

 acetic, iron-haern. + orange, x 400. 



Fig. 8. — Portion of a section through the wall of a vessel in tiie "rete 

 mirabile." The actual diameter of the lumen is much less, but it is less 

 obstructed by spongy tissue. Corr. subl. + acetic, iron-hseai. -f orange. 

 + 400. 



Figs. 9 and 10. — Adults of C, minchinii attached to the ccelomic epi- 

 thelium, which they have invaginated ; {b) shows where this is reflexed 

 internally, {a) being the part of the parasite still uncovered. Fig. 9 seen in 

 optical section; corr. subl. + ac, carm.-alum ; Fig. 10, as a transparency; 

 Flemming, para-carmine. Both X 150. 



Fig. 11. — Portion of retractor muscle, siiowing three C. minchinii com- 

 pletely encysted. The small one at («) is most imbedded, x 80. 



PLATE 2. 



Mode of life and general apjjearance (continued). C. minchinii. (All 

 figures except fig. 20 relate to this parasite.) 



