770 
ME. H. N. MOSELEY ON THE STEUCTUEE AND 
bend. If the right duct (Rd) were gradually pulled upon and every thing supposed 
free, the original condition of affairs would be restored, the penis would lie in the 
middle line, and the sharp turn be taken out of the left duct ; both ducts would pass 
under a single nerve-cord, one on each side. The present arrangement appears to be a 
commencement of the unilaterality found in Scolopendridse. In two of the males 
opened, merely to observe the sex, one testis with its accessory gland and vesicula 
seminalis was much larger than the other, showing a further step towards unilaterality. 
The testes are packed in the body one a little way above the other beside and behind 
the intestine. 
The convoluted tube above the testis contains no spermatozoa or vesicles of evolu- 
tion, but only large fine granulated or transparent gland-cells, being, in fact, very like 
in structure to the slime-glands of the animal. These tubes are probably diluent 
accessory glands of the testis, and might be called “ prostates.” 
The testes examined contained abundance of vesicles of evolution, with spermatozoa 
in various stages of development. The structures observed are shown in Plate LXXIV. 
figs. 2, 3, & 4. The earliest forms of the cells which produce the spermatozoa appear to 
be those seen in fig. 2, connected together in a row and filled simply with fine granules. 
The cells are flattened by mutual appressure, and probably multiply by division. The 
cells enlarge and acquire a transparent nucleus. In the next stage observed the cells 
are again enlarged, and contain from three to as many as six vesicles of evolution, 
sometimes only one or two ; these are shown in fig. 3, a , b, c , as seen with a PIaktnack’s 
No. 10, ocular 4. The large cells have perfectly transparent contents without granules. 
The contained vesicles of evolution are ovoid in form, and have a fine granulated 
ovoid nucleus : they are transparent over the greater part of their area, but arranged 
irregularly ; about one pole is a single layer of fine distinct granules. In the next 
stages the vesicles of evolution are full of granules, and the filaments of the sperma- 
tozoa are formed curved around the ovoid nuclei. This stage is represented very much 
enlarged in fig. 3 ,d. The short tails of the spermatozoa project from the parent cell. 
a, b, a , fig. 4, show further stages, these being the most abundant forms in the testis. The 
granular matter and wall of the vesicles of evolution have almost disappeared. The 
tails of the spermatozoa are longer. The number of spermatozoa developed in each 
cell is very variable ; cells with only one, as in Plate LXXIY. fig. 4, a, are very common. 
In the next (fig. 4, c, d , and e ) stage the spermatozoon is free from the cell ; the nucleus of 
the vesicle merely remains attached to it laterally within its loop. Some fine granules 
are often to be seen in the space between the nucleus and the loop of the spermatozoon, 
the remnants of the granulation of the vesicle of evolution. None of the spermatozoa 
are found freed from their nucleus within the testis, and most of them retain the nucleus 
in the vesiculee seminales. In the mass of spermatozoa contained within the penis or 
terminal ejaculatory duct, about half of the spermatozoa had thrown off the nucleus, 
and the other half retained it still. Free nuclei abounded in the mass. The ripe 
spermatozoa met with in the ovary of the female are always simply filamentary, like 
