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shape of the follicle, the Purkinjean vesicle, and the vitelligenous cells 

 heing very similar ; but whereas in Coccus and in all insects the egg- 

 follicle projects from the ovary, in Glomeris and the other Myriapods, 

 so far as my observations go, the follicle projects into the ovary. If, 

 therefore, we consider the ovary as consisting of an outer membrane 

 and an inner epithelial layer, it would appear that while the egg in the 

 Myriapods arises between these two layers, in the insects it originates 

 on the inner side of both. 



This difference appears to me to be very important, and, as will be 

 mentioned under the head of lulus, escaped the attention of our great 

 anatomist Newport, whereby he was led to give an erroneous descrip- 

 tion of the ovary of that genus. I have chosen to compare Glomeris 

 with Coccus, because the vitelligenous cells make the resemblance, 

 and, at the same time, the difference between these two genera more 

 striking. If we, however, compare with them the ovary of Phalan- 

 ffium, we shall see not only that the vitelligenous cells are absent, but 

 that the egg-follicle differs equally from that of the insect on the one 

 hand, and that of the Myriapod on the other. The egg-follicle projects 

 fromihe ovary as in Coccus, &c. ; but, on the other hand, the Purkinjean 

 vesicle lies on the outer side of the epithelial layer, as in Glomeris, 

 and in consequence the egg-follicle, which in Coccus consists of both 

 the ovarian membranes (so far as the epithelial layer can be called a 

 membrane), and in Glomeris of the epithelial layer only, is in the 

 Phalangidse, and perhaps all the Arachnida, formed only by the 

 outer membrane. Consequently, while in the insects the mature ovum 

 passes into the ovary through the neck of the follicle, in Myriapods 

 and the Arachnida it bursts through the epithelial layer, in the former 

 at its free, and in the latter at its attached end. 



If these characteristics are found eventually to hold good through- 

 out the Myriapods and Arachnida, the differences thus shown to 

 exist between these groups will be of great interest ; but it is too early 

 to generalize on the subject with much confidence. Moreover, it often 

 happens that one or a few epithelial cells are attached in Arachnida 

 to the inner side of the follicle-wall. This happens, however (as far 

 as my observations go), without any regularity, and the cells thus 

 present fulfil perhaps no important function in the formation of the 

 egg. The Crustacea appear to differ from the three preceding groups 

 in the fact that their eggs do not possess separate follicles. 



