510 W. H. Coe — Anatomy of Cerehratulns lacteus. 



Figure 4. — Transverse section through the intestinal region. The genital duct {gdf) 

 leads into the thin-walled genital sac {gs) from vrhich all the genital products have 

 been discharged. The dorsal vessel {dh) lies beneath the proboscis-sheath {ps) 

 and the lateral blood-vessels {Iv) occupy a position beneath the intestinal caeca {ic) 

 and on either side of the main intestinal canal ; x 8. 



Figure 5. — Cells from the oesophagal epithelium isolated by maceration in a 0.2 per 

 cent, aqueous solution of formalin and stained with Delafield's hsematoxylin. The 

 cilia which cover the outer, free surfaces are not shown ; x 150. 



Plate XII. 



Figure 1. — Horizontal section through the head to show the attachment of the pro- 

 boscis at X. The proboscis {p) is in its normal position and the cephaUc lacunae 

 {d) are normally distended; x 20. Compare Plate XI. fig. 2, in which the 

 proboscis is everted. 



Figure 2. — A portion of the same section nfbre highly magnified. The sphincter (rs) 

 is seen at the posterior end of the rhynchodaeum {r) and separates this chamber 

 from the cavity of the proboscis {pl)\ a;, attachment of proboscis; 6r, brain (cut 

 somewhat obliquely) ; cZ, cephalic lacuna ; re, rhynchocoelom; x 55. 



Figure 3. — Macerated cells from the epithelium of the proboscis; a, " rhabdite-cell " 

 with a row of rhabdite-like bodies in the upper portion ; ?'o, some of the extruded 

 "rhabdites;" a', one of the gland-cells which usually lie somewhat below the 

 "rhabdite-cells;"' x 250. 



Figure 4. — Epithelium from the proboscis; e, epithehum ; Im, basement membrane. 

 The outer row of nuclei are those of the "rhabdite-cells," the others belong 

 mostly to gland-cells. The " rhabdites " are seen as a dark band near the free 

 border; x 125. 



Figure 5. — Diagram of the principal layers of the body-wall; e, integument including 

 cutis and epithelium; Ini', outer longitudinal muscles; np, nerve-plexus; cm, 

 circular muscles ; Im, inner longitudinal muscles. 



Figure 6. — Diagram of the layers in the proboscis for comparison with those of the 

 body-wall in figure 5 ; e, epithelium Uning the lumen of the proboscis ; hn, inner 

 longitudinal muscles; np, nerve-plexus; cm, circular muscles; Im', outer lon- 

 gitudinal muscles ; cm% outer circular muscles; en, endothelium bathed in the 

 rhynchoccelomic fluid. 



Figure 7. — Part of a transverse section of the proboscis-sheath. The endothelium {en) 

 rests upon a very thick basement membrane (&m); Im, thick layer of longitudinal 

 muscles ; cm, circular muscles separated from the outer longitudinal muscles Qm') 

 by a layer of loose connective tissue (c) ; x 140. 



Figure 8. — Ciliated epithelium of the rhynchodaeum. The cells are arranged with 

 great regularity, with their nuclei near their bases; x 175. 



Figure 9. — Corpuscles from the rhynchoccelomic fluid. 



Figure 10. — Posterior extremity of the proboscis of a small specimen; x 4. 



Figure 11. — Transverse section through the anterior end of the proboscis. Ciliated 

 columnar epithelium (e) lines the four-lobed lumen {pi). The muscles {m) are all 

 longitudinal, and the nerves {pn) are situated to the right and to the left of the 

 lumen in the midst of the muscles ; en, outer endothelium ; x 1 8. 



