122 CALIFORNIA ACADKMY OK SCIENCES. 



PLATE XLV. 



ECLIPIDRILUS FRIGIDUS. 

 107. A transverse section, the storage chamber more hiyhly magnified. Zeiss Horn. Im. 1-12 Eyp. .3. 155. pr.yl.l. 

 larj-e prostate glands, pr. <jl. n. small prostate glands. /. m. longitudinal muscles, arranged in btrands. 

 t. m. transverse muscles. «. nuclei of inner lining epithelium. 



108A. A dissected ovary. 



108B. A ripe ovum. 



109A. A dissected oviduct. 



109B. Longitudinal section of the body-wall, at the ovipore, showing the latter to be situated in the intersegmental 

 groove. 



110 to 124. Various and successive stages of development of spermatozoa. 



110. A resting spermatogonium (spermatospore) from the testes. 



111. A spermatogonium from the outer edge of the testes ready to fall ofl'into the sperm-sac. The chromosomes of 



the nucleus have begun to develop into winding rods. 



112. Nucleus from a spermatogonium from the sperm-sac. 



11.3. Spermatogemme (spermatosphere or spcrmpolyblast). The spermatocytes (spermatoblasts) are surrounding 

 and attached to a central, non-nucleated cytophore (or spermblastophore). 



1 14. The same shortly before division of the spermatocytes. 



1 17. A spermatogemme in the next last stage of development. The spermatocytes have through division reached 

 their final number. The cell divisions are indistinct. The nuclei are globular with scattered chromosomes. 



118. A further developed or next last stage of the spermatogemme. The i.uclei have assumed an ovoid shape, stain- 

 ing very dark with saflfrauiu. 



1 l!l. .\ part of a spermatogemme, last stage. The nuclei have again diminished in size and become perfectly round, 

 previous to growing out into spermatozoa. 



120. Part of spermatogemme in which the nuclei of I I'J have begun to grow out into spermatozoa. 



121. A fully developed spermatogemme with grown spermatozoa attached to the cytophore. 



122. The same in a state of dissolution, the spermatozoa detaching themselves. 



123. Spermatozoa fully developed, the nuclear end being only slightly thicker than the other part of the body. 



124-125. Sections of fully developed spermatogenimes, showing spermatozoa in cross-section, they having gradually 

 diminished in diameter since the nuclei were first concentrated (fig. 119). but having proportionately grown 

 in length. 



126. Nuclei from 11.3, 117, 118, show their relative size. 

 127-129. Yolk sac with yolk cells. 



127. The whole sac in section. Zeiss C. 



128. Yolk cells without granulation. 



129. Further developed yolk cells with granulation. 



KERRIA McDONALDI. 



130A. Longitudinal section of the alimentary canal of Ki rriu MrDoiiiihli in the somite next posterior to the male 

 aperture, showing unicellular glands alternating with ciliated epithelial cells, y/. unicellular glands. 



130B. A more highly magnified part of the former, showing one of the unicellular glands, surrounded by common 

 epithelial cells, also rudimentary glands, r. yl. ludinjontary glands, i/l. large gland. /). its poie. rp. 

 epithelial cells, hi. o. blood-lacuue. /. m. longitudinal muscles, i. m. transverse muscles. 



