TJic Anatomy of Opistlioimtus cinctipes. 85 



cut twice in the region of the posterior loop just before {I'.v.d'^) and 

 after {iw.cP) it passes under the nerve cords (indicated by the hne 



X y in fig. 15). It i^esembles the unpaired portion in section, 



except that its nuclei are larger and less numerous. 



In my sections through the vas deferens the whole of the unpaired 

 region and a considerable portion of the paired tubes contained a 

 curious, highly stainable structure {sper, fig. 28), which appeared as- 

 if made up of numerous little vesicles densely packed together and 

 surrounding one or several yellowish central bodies. At the place 

 where the unpaired vas deferens branches this structure also branches 

 into two, each branch being continued into the paired vasa. It was 

 not present in the ductus ejaculatorius. The whole of this structure 

 evidently represents a large elongated spermatophor and is com- 

 posed mainly of a great number of closely packed spermatozoa, each 

 of which apparently consists, as in Peripatus, of a highly stainable 

 nuclear filament to which a rounded lump of slightly stainable 

 protoplasm adheres, similar to those figured by Gaffron (1885, fig. 58). 

 These adhering masses of protoplasm form the numerous vesicles 

 referred to above, while the deeply staining meshwork between them 

 is composed of the nuclear filaments of the spermatozoa. The nature 

 of the yellowish central bodies could not be made out. The portions 

 of the spermatophor lying nearest the testes are composed merely of 

 closely packed spermatozoa, but more posteriorly, at least in the 

 unpaired portion of the vas deferens, the spermatozoic mass ia 

 encased in a thin deeply staining sheath, but there is no external 

 layer of granules corresponding to those found by Gaffron in 

 Peripatus. At one place in the unpaired vas deferens the outer 

 sheath of the spermatophor was suddenly and strongly constricted 

 for a very short distance, and here its walls became very thick and 

 its lumen narrow. There were no spermatozoa in the constricted 

 portion, which thus resembled the narrower parts of the axial tube 

 of the spermatophor of Pei-ipatus, figured by Gaffron (1885, fig. 73). 



Large elongated spermatophors have hitherto been found only in 

 Peripatus and Peripatoides, in which genera the unpaired part of the 

 vas deferens is enormously elongated, whereas in 0. ciiictipes this- 

 part is comparatively short. 



9. The accessory glands " of the male. 



The accessory glands of the male consist of four tubes, unusually 

 complicated in structure and arrangement and opening externally by 



* By accessoiy glands I mean only those which occur in the genital and post- 

 genital segments of the male. 



