108 CALIFORNIA ACADEMY OF SCIENCES. 
64. 
69. 
PLATE XXXVIII. 
PONTODRILUS MICHAELSENI. 
Section through the body in somite xi, showing the sperm-sacs and their relative position. s. anterior septum. 
d.v. dorsal yessel. h. hearts. @. wsophagus. v.v. the branched ventral vessel. sp.s. the racemose 
sperm-sacs situated much ventrally of the intestine. x. c. ventral nerve cord. J. m. and ¢. m. longitudinal 
and transverse muscles of the body. 
A cross-section of the same region more magnified. s. x/xi. septum between x/xi. s. xi/xii. septum between 
xi/xil. sp.s. one of the sperm-sacs. spz. spermatozoa. m.c. mother cells. c. r. ciliated rosette. m. m. 
muscles connecting the septum below the sperm-sac with the cesophagus. 
A more longitudinal section of the ciliated rosette, showing the muscles and the blood vessels in the thick 
funnel. 
Another section through the ciliated rosette, showing the thick layer of blood vessels below the ciliated 
epithelium. 
A cross-section through the glandular part of the prostate, uear the entrance of the spermduct. ep. epithelial 
cells with round nuclei. c. m. circular muscles. c. glandular cells. m. muscles connecting with the body- 
wall. sp. d. spermduct. 
Cross-section through the muscular part of the prostate. 
