24 C. HERBERT HURST, 



on the inner surface of this layer, supplying certain small rounded 

 cells lying between this layer and the base of the shaft. 



All the cellular layers of this organ are epidermal in origin, but 

 the layer which I have called ganglionic stands, during the later 

 part of pupal life, in direct continuity with the superficial layer of 

 cells of the " brain," and this layer in turn is continuous with the 

 deep layer of the epidermis of the head immediately behind the 

 base of the antenna. Whether the continuity of the ganglionic 

 layer of the organ with the brain is due to identity of origin, both 

 being budded off from overlying epidermal cells, or to migration of 

 cells from the brain into this organ, is difficult to determine, but 

 the cells of the cerebral lobes (" hemispheres ") are larger than those 

 of the cup-like organ, while the latter resemble the cells of the 

 inner optic lobes very closely in size and in mode of staining. 



This organ is already a conspicuous object in sections of the larva, 

 more conspicuous indeed than the "brain," but the differentiation 

 of the layers is only completed late in pupal life. 



The Eeproductive System. 



I. The male generative organs of the adult consist of testes, 

 vasa deferentia, " prostatic glands," copulatory organ with a common 

 pouch at its base, and two pairs of gonapophyses. Of these last 

 the outer ones are a large pair of forceps for holding the female. 

 Both pairs are probably segmental appendages, and I have already 

 spoken of their origin in the larva. 



The testes are a pair of cylindrical bodies already present in the 

 larva at the sides of the intestine in the sixth segment. They are 

 chambered, and the spermatic elements in the hinder chambers are 

 more advanced than those in the anterior chambers. The length of 

 each testis is that of the segment in which they lie. 



The vas deferens of each side is a direct continuation of the wall 

 of the testis, and is a very narrow tube running backwards, quite 

 distinct from its fellow of the opposite side, but the two are closely 

 bound together in their hinder parts, and they open behind into the 

 common pouch. 



The prostatic glands are a pair of elongated glandular tubes, 

 apparently simple, but seen in sections to be double, though the 

 cavities communicate behind before opening into the common pouch. 



