I20 WHEELER. [Vol. VIII. 



proximally and end in terminal ampullos, which are from 

 the first somewhat smaller and more elongate than the homo- 

 dynamous structures of the male. The appendages to which 

 the ampullce belong are also less prominent than the tenth 

 pair of appendages in the male. Examination of several 

 series of cross-sections from embryos in Stage J — this being 

 the stage in which the sexes differentiate — reveals the curious 

 fact that in the female, besides the pair of ampullae in the sev- 

 enth, a pair is also retained in the tenth segment. Figs. 58 and 

 59 represent two sections taken from such an embryo — the 

 former passing through the tenth, the latter through the seventh 

 abdominal segment. In Fig. 58, the two terminal ampullae 

 Ua. m), and small portions of the ducts leading to them, are 

 still preserved, but the cells and nuclei, especially in the ducts, 

 are being broken down. The ampullae soon share the same 

 fate. In the seventh segment (Fig. S9,f.d.) the cavity of the 

 diverticulum still opens into the ccelomic cavity of the same 

 segment (coe). Its distal ampullar end is applied to the ecto- 

 derm where it bulges out to form the small seventh abdominal 

 appendage {ap7). The condition of the diverticulum after the 

 constriction of its proximal portion is shown in Fig. 60, taken 

 from a somewhat more advanced embryo. In this figure, the 

 connection of the oviduct with the posterior end of the young 

 ovary {ov.) is distinctly seen. The cells of the duct pass over 

 into the epithelial cells of the ovary, just as the cells of the 

 spermaducts become continuous with the testicular epithelium. 

 We may now turn to surface views of the female reproduc- 

 tive organs. The specimen represented in Fig. 48 is in the 

 same stage as the male embryo represented in Fig. 42. Five 

 consecutive pairs of abdominal appendages are still present 

 {apl, ap^^). Of these, the ninth and eleventh pairs are very 

 prominent, while the tenth pair has grown very small. The 

 ovary {ov) extends back to the seventh segment where it joins 

 the oviduct. This ends in the terminal ampulla, which lies near 

 the posterior edge of the segment in the seventh abdominal 

 appendage. The terminal ampullae of the tenth segment have 

 not yet disappeared. They are represented in blue because I 

 regard them as the homologues of the persistent male ampullae. 



