104 CALIFORNIA ACADEMY OF SCIENCES. 



PLATE XXXVT. 



PONTODRILUS MICHAELSENI. 



46A. Sectiou throuf^Li the nuliiiifutary gizzard or thickening of the iutestiual wall in suiuite v. 



46B. One of the circular muscular strands of the former figure. 



460. Section of the alimentary wall adjoining posteriorly to the rudimentary gizzard in somite vi. 



47. A longitudinal section through the intestine showing the glandular-crop in somites xiv, xv, xvi, and the be- 



ginning of the sacculated intestine in xvii. d. v. dorsal vessel, d. v. c. connection between the dorsal vessel 

 and the vascular system of the crop. gl. cr. glandular crop. hi. s. blood sinus in the outer layer of the 

 glandular layer, gl. c. glandular cells constituting the bulk of the crop. do. chloragogen cells, m. I. the 

 two muscular layers, t. i. the end of the tubular intestine or oesophagus. 



48. A section of the former more highly magnified, showing the glandular cells which constitute the crop aud the 



branched lumens which are especially pronounced in the outer part of the layer. I. m., t. m. the two mus- 

 cular layers, which here are not more develojjed than in any other part of the intestine. 



49. Cross-section through the glandular crop in the posterior jjart of the organ in somite xvi. In this section only 



few of the glandular cells are found. 



50. A section anterior to the former, but in the same somite. Here many more of the glandular cells arc seen. In 



these two sections the chloragogen layer is thick and the cells crowded, similarly the ridges of the epithelial 

 cells aie high and separated by deep grooves. 



51. A similar cross-section through the crop in somite xv. Both the chloragogen cells and the epithelial cells are 



lower. 



52. Another cross-section showing the entrance of a blood vessel from the dorsal vessel into the vascular system 



of the glandular crop. 



5.3. A part of the glandular cells of the crop more highly magnified showing the structure of the cells and the 

 branched lumens between them. gl. c. glandular cells. /. lumen, hi. blood sinus. ep. inner epithelial 

 cells. 



54. An oblique section through the surface of the crop showing the two muscular layers, a blood sinus and a few 

 chloragogic cells cut through. The glandular cells immediately below are not delineated. 



