44 



OSBORN. [Vol. XVIII. 



EXPLANATION OF PLATE II. 



Fig. 28. Transverse commissure and related parts in horizontal sec- 

 tion, X 160. 



Fig. 29. Section of eye from same series as Fig. 6, X 850. 



Fig. 30. Cuticle, tangential section, near anterior end, X 850. 



Fig. 31. Cuticular sense-organ, in vertical section, X 1600. 



Fig. 32. Marginal organ, section passing in its length, X 567. 



Figs. 33, 34. Uterus and cirrus sack, in two neighboring sections of 

 horizontal series, X 180. 



Fig. 35. Junction of spermatic duct and seminal vesicle, from specimen 

 killed in corrosive under compression and stained with Ehrlich's hsema- 

 toxylin, X 180. 



Fig. 36. Walls of spermatic duct and seminal vesicle, with concretion 

 in former, from section, X 850. 



Fig. 37. Median section of spermary, sagittal series, picro-nitric, iron- 

 hsematoxylin, X 320. 



Fig. 38. Two parietal cells of spermary, animal killed in May, corrosive 

 sublimate, iron-haematoxylin, X 850. 



Fig. 39. Central cell from same section as preceding, X 850. 



Fig. 40. Parietal cell from same series as Fig. 37, picro-nitric, iron- 

 hasmatoxylin, X 850. 



Figs. 41, 42, 43, 44, 45. Central cells from same spermary as Fig. 40, 

 showing various stages of spermatogenesis, X 850. 



Fig. 46. Central cells of spermary, spermatogones (?), showing centro- 

 somes (?), corrosive, iron-ha^matoxylin, X 850. 



Fig. 47. Karyokinesis in spermatogones, stage between 43 and 44, from 

 same series as 40-45, X 850. 



Figs. 48, 49. Two spermatogones from still another series, showing stages 

 of karyokinesis, picro-nitric, iron-hjematoxylin, X 850. [270. 



Fig. 50. Ovary in longitudinal section, cut in plane of " tuba fallopii," X 



Fig. 51. Longitudinal section of part of " tuba," X 850. 



Fig. 52. Parietal cell of ovary in July, X 850. 



Figs. 53, 54, 55, 56. Cells from different parts of the same ovary showing 

 development of the ovum, picro-nitric, iron-hsematoxylin, X 850. 



Fig. 57. Follicle of the vitellaria, in median section, from same series as 

 Figs. 52-56, X 567. 



Figs. 58, 59, 60, 61. Cells from follicle of vitellaria in different stages of 

 maturation, from the same series as the preceding, X 850. 



Fig. 62. One of the yolk-cells from the yolk-receptacle, X 850. 



Fig. 63. An egg from life, X 220. 



Fig. 64. Yolk-cell in egg in uterus, from section, corrosive, iron-haema- 

 toxylin, X 850. 



Fig. 65. Embryo from same egg as 64, showing two nuclei but no divis- 

 ion of the cytoplasm, X 850. 



Figs. 66-74. Surface views without camera from embryos in eggs, the 

 time of development being as follows : Figs. 66, 67, 68 and 74 are from the 

 same parent, the first at the time of deposit, the rest at eighteen hours, 

 forty hours and six days later respectively. Figs. 69, 70, 72 and 73, from 

 another parent, are forty-eight hours, forty-eight hours, ninety hours and 

 one hundred and fourteen hours old respectively. Fig. 71, from a third 

 parent, is sixty-six hours old. 



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