POINTS OF THE ANATOMY OP POLYXENUS LAGDRUS. 3] 



tbe internal surface of the deutomalge in the same position as 

 those of Julus and other Chilognaths. I have not thought it 

 necessary to give a figure. 



The Nerve-cord. 



The nerve-cord shows a greater resemblance to that of the 

 larval Julus and also of Chilopods than does the nerve-cord of 

 any other Chilognath with which I am acquainted. Between 

 the ganglia the fibrous part of the ventral nervous system is 

 divided into two distinct cords as shown in figs. 5, 6, and 12. 



The Internal Generative Organs. 



In both male and female the generative organ has the form 

 of a long tube, which communicates with the exterior by two 

 short oviducts or vasa deferentia. The female organ (fig. 6) 

 consists of a long tube, formed of a single layer of cellular 

 membrane, and containing the spongy connective tissue (or 

 stroma) within which the ova are produced. Some of the 

 cells of this tissue become ova, while others, indistinguishable 

 at an early stage, form the follicles which surround the ova. 



At its anterior end the ovary becomes constricted, as shown 

 in fig. 5. Its walls increase in thickness, and are composed of 

 two layers, an external and an internal, the latter consisting of 

 larger cells. Just at the point of division into the two ovi- 

 ducts two large receptacula seminis communicate. They are 

 composed of a single layer of cells (fig. 5, rec. sem.), and con- 

 tain spermatozoa, as shown in the figure. 



The male generative organ also consists of a tube, the 

 testis, which divides anteriorly into two vasa deferentia. The 

 walls of the testis are formed by a single layer of cells, and 

 within it is a mass of spongy connective tissue from the cells 

 of which the sperm-cells and the follicles arise. The sper- 

 matozoa originate by a sperm morula (fig. 7), and the morula 

 is surrounded by a follicle which may perhaps serve to secrete 

 the covering of the spermatophores which are formed inside 

 the follicles. The spermatozoa are long and thread-like, re- 

 sembling those of Lithobius and Scolopendra. 



