44 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the rudiments of the penis and the valvar at each side. Later, the two 

 penis-rudiments fuse in each case in the middle line to form a single 

 structure. From this point the development differs in the two orders. 

 In the Hymenoptera, the genital pocket persists, and the penis and 

 valvae remain close to one another. In the Trichoptera, the genital 

 pocket disappears, the penis, owing to the development of a secondary 

 invagination, sinks into the abdomen, while the valvae advance to the 

 surface. In other words, the male genital apparatus in Hymenoptera 

 remains in a far more primitive condition than in Trichoptera. 



New Collembola.* — Carl Borner describes a number of new forms, 

 one of which he places in a new genus as Willemia anophthalmia. The 

 characters of the new genus are as follows : — Shape of body as in 

 Aphorura ; antennae cylindrical ; the fourth segment with olfactory hairs 

 but no olfactory papillae ; post-antennal organ present, but eyes entirely 

 absent ; mouth-parts biting ; tarsus with two claws ; furca and tena- 

 culum entirely suppressed ; two anal spines placed on small papillae. 

 The author also founds a new sub-family of the Achorutidae, under the 

 name of Neanurinec, for the following genera : — Pseudachorutes, Apho- 

 romma, Anurida, and Neanura, all of which have primitive ocellae, and 

 not ommatidia as in the sub-family Achorutinae. 



j8. Myriopoda. 



Development of Scolopendra.j — Dr. E. Heymons has been successful 

 in breeding from S. cingulata and *S'. dahnatica in captivity, and thus 

 obtaining abundant material of eggs and embryos. He finds that the 

 female coils herself round the eggs after these are laid, and that the 

 presence of the mother is essential to hatching. He ascribes this partly 

 to the glandular secretion with which she lubricates the eggs, partly to 

 the fact that her presence prevents the eggs coming into immediate 

 contact with the surrounding soil. 



The embryological part of the paper is so comprehensive that some 

 only of the more general of the results can be indicated here. In 

 regard to the segmentation and the formation of the germ-layers, the 

 author is of opinion that, anomalous as these processes seem in Scolo- 

 pendra, they may without difficulty be homologised with those of Anne- 

 lids, the differences being due to the great development of yolk in the 

 Myriopods. In Scolopendra the method of formation of the blastoderm 

 is to be regarded as due to a modified epibole of yolk-laden macro- 

 meres by yolk-free micromercs. As in Annelids and in Arthropods in 

 general, it is possible to divide the body into three regions, a head- 

 region or acron ( = prostomium of Annelids), which is without appen- 

 dages or ccelomic cavities, a terminal telson ( = end-segment of Anne- 

 lids), of which the same is true, and between these extremes a series 

 of metameres furnished, during embryonic life at least, with paired 

 appendages, with paired ccelomic cavities, and with paired ganglia. Jn 

 Scolopendra there is also for a long period an undifferentiated zone 

 between the last (30th) metamere and the telson, which is homologous 

 with the zone of budding in lower forms. The author's results lend no 



* Zool. Anzeig., xxiv. (1901) pp. 422-33 (0 figs.). 



t Zoolngica, Leipzig, xiii. (1901) pp. 1-244 (S pis and 42 figs.). 



