NOTE ON A NEW BKITISH EOHIUEOID GEPHTREAN. 383 



EXPLANATION OF PLATES 27 & 28, 



Illustrating Professor W. A. Herdman's paper on "A New 

 British Echiuroid, Thalassema Lankesteri, n. sp. 

 (Herdman)." 



Reference Letters. 



cl. Cloacal aperture, c. Cuticle, c. n. Cloacal nephridia. ep. Epidermis. 

 d. Dermal layer of skin. /. Ciliated funnels of posterior nephridia. int. 

 Intestine. I. n. Left anterior nepliridium. m. Mouth, mes. Mesentery. 

 muse. Muscular layer of body-wall. «. Anterior nephridium. n. c. Ventral 

 nerve-cord. n. s. Nephrostome. ces. (Esophagus, ov. Ovary, p. Groups of 

 rounded pigment masses of a green colour in the dermal layer of skin. p. I. 

 Pre-oral lobe or " proboscis." r. n. Eight anterior nephridium. r. Rectum. 

 s. Genital seta. u. Uterine part of nephridium. v. v. Ventral blood-vessel. 

 to. Body-wall. 



PLATE 27. 



Thalassema Lankesteri, n. sp. (Herdman), 



Fig. 1. — Specimen A. Natural size, from left dorsal side. 



Fig. 2. — Specimen B. Natural size, showing the green colour. 



Fig. 3. — Specimen C. Natural size, from ventral side. 



Fig. 4. — Restoration, to show probable appearance of the species. 



Fig. 5. — Ventral view of anterior end of Specimen A, to show base of pro- 

 boscis and genital setae. 



Fig. 6. — Posterior end and cloacal aperture, to show papillae on surface. 

 X 2. 



Fig. 7. — Anterior end of speeimen, dissected from right side, to show 

 alimentary canal and other organs. 



Fig. 8. — Anterior part of alimentary canal, with anterior nephridia, &c., 

 isolated, from ventral surface. 



Fig. 9. — Diagram of course of anterior part of alimentary canal. 



Fig. 10. — A few convolutions of alimentary canal, to show the silky 

 mesenteries. 



Fig. 11. — Piece of a mesentery, enlarged. 



Fig. 12. — Small part of same mesentery, magnified (x 50). 



Fig. 13. — One of the genital setae, enlarged. 



Fig. 14. — Part of a section through the skin, to show the position of 

 the pigment masses {p.) which give rise to the green colour (x 300). 

 VOL. 40, PART 3. — NEW 8BK. D D 



