On Two Orders of Arachnida; Opiliones. Especially the Suborder Cyphophthalmi, and Ricinulei, Namely the Family Cryptostemmatoidae (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: Abdomen in Laniatores 13 value of "corona analis" (woodcuts figs. F?H) in Nemastomatoidae, and Troguloidse1. Thorell, on the contrary (a p. 458), unhesitatingly interpreted the " anal plate " in Laniatores and in the families Phalangioidae and Ischyropsalidoidse amongst Palpatores, as well as the hindmost piece in " corona analis" in NemastomatoidDe and Troguloidse, as a tergite, and accordingly counted nine abdominal segments in Laniatores and Palpatores, in which view he was followed by Simon (b, p. 118), though with some vacillation. As, however, several difficulties have to be solved, particularly as regards the sternites in the order Opiliones generally, we have thought it well to subject the question to a thorough examination. In the other orders of Arachnida, where the division of abdomen into segments is clearly to be seen, tergites and sternites are placed opposite each other so plainly that it is easy or, at any rate, not difficult, to see which sternite belongs to each of the tergites. But this is not the case in Opiliones where the sternites as a rule are not placed opposite the corresponding tergites, so that it is impossible to find out which sternites belong to each of the tergites without a comparative study of various animals. We shall therefore examine in order the different combinations which occur. As regards Laniatores we may premise that we can speak with some confidence because one of us has studied these animals for many years, and is acquainted with a considerably larger number of them than have been described. Amongst the families of this sub-order the very remarkable one, Oncopodoidse, established by Thorell, exhibits an arrangement different from what occurs in any of the other families. Cephalothorax coalesces here with the first eight2 ter...