BOTH THE SEXES IN DIPTEEA. 36!) 



B)'(i>d'uJ(B. — In the male of Braula cceca, Nitz., the minute parasite of Apis mellijica, 

 small as it is, I can trace the appendages, and they appear of more Muscid type than 

 the genitalia of Melophagm. 



NycterihiidcB. — The Nycteribiidse are a difficult group to study, and I have only had 

 access to some preparations in the British Museum, and have had no opportunity of 

 making dissections, the only satisfactory way of studying genitalia. 



Tiie male of Nyctcrihla Dnfourii, Westw., has a large pair of forceps, quite ventrally 

 placed, articulated at their bases ; their points are highly chitinized, and are not unlike 

 those of Glossina palpal is. The penis is small and the apodemes cannot be differentiated. 

 There are many spines in the region of the laminse superiores, but no actual plate ; 

 laterally there are two bulbous processes very thickly spined. 



The ovipositor cannot be said to exist in the Pupipara, but there are relatively large 

 processes at the extremity of the abdomen of the female. 



In Cyclopodia Hopei, parasitic on one of the flying-foxes, the male has a rather pointed 

 abdomen ; on the ventral side of this are articulated a neat pair of forceps which meet 

 at their points and quite cover the cavity of the hypopygium. Between their bases 

 two small chitinous knobs can be seen. There are no lobular spined processes as in 

 N. Dufourii, but the segment opposite the forcipes has a short row of blunt spines on 

 its edge, which represents the laminae superiores. The female cannot be said to have 

 valves, but has two large tubercles situated dorsally and ventrally on the extremity of 

 the abdomen ; the larger is on the ventral side and is tufted with bristly hairs, and that 

 side of the abdomen has many long strong spines. 



In another species of this genus, also parasitic on a " flying-fox," labelled Nycteribiu 

 Weshooodii, in the Cabinet of the Quekett Microscopical Club, the forceps are more like 

 those of N. Dufourii ; it has the row of blunt spines representing the laminae superiores, 

 but no lateral processes. This specimen, which has been cleared and mounted under 

 pressure, shows in the interior a very large aculeated membrane, with long chitinous spines 

 and a strong apodeme, which appears to be the penis, but no appendages can be made out. 



Similarity of Appearance of Genitalia and ][Jouth-parts in Diptera. 



A person acquainted with the mouth-parts of Flies, particularly with the armatm-e of 

 SimuUum and Tahanns, must be struck, when examining the genitalia of the Muscidae, 

 by a similarity of appearance and arrangement. In both he finds a central organ 

 surrounded by aculeate and setose appendages, and in both the central organ pierced by 

 a tube or duct. It occurred to me that these parts, so widely separated in situation, 

 were intimately connected, and that they were both influenced by an identical law of 

 growth and development. 



By " identical law " I mean such a law as governs the growth of the number of joints 

 on the limbs ; a law not absolutely inelastic or immutable, as can be seen in the tarsi, 

 where, though five joints are generally found, a lesser number is sometimes met with. 

 It regulates the growth of the appendages of both extremities. 



Quite different from this law is that which governs the secondary sexual characters 



