Can I put my UVB light directly on my screen top?

[brooklyn2301]

I recently had to buy a new lamp and the UVB bulbs stick out slightly at the bottom. I can't hang it up because I have very tall ceilings. Would it be okay to let them sit on the cage lid directly? If not, any suggestions on how should I set them up?
Here are some pictures just in case I didn't explain it well.

 

[KarrieRee]

What size tank ? Is it a tall tank ? The UVB should be inside the tank as it looks like its fine screen mesh-- here is the lighting that is recommended here on the forum---
Which UVB light should I use?
The best UVB light is a ReptiSun 10.0 fluorescent tube HO (Or Arcardia 12% in the UK). Compact or coil bulbs do not emit the proper amount of UVB light for a bearded dragon, and should not be used. Other brands, such as the Zilla Desert Series and ReptiGlo have been known to cause eye problems and other health issues with bearded dragons, and should be avoided. The reason that some UVB lights (Zilla, ReptiGlo, coils/compacts, ect.) are considered dangerous is because the wavelength of UVB that they emit is shorter and more intense than the wavelength of the "safe" lights (ReptiSun, Arcadia).
UVB lights should be replaced every 6 months. The T5’s are a strong bulb and only need to be replaced once a year – the T 8 every 6 months--- where as the T 8 are not as strong—they need to be placed inside the tank the T 5 10.0 bulb approx 10-11 inches from basking spot – the T 8 approx 6-8 inches from basking spot—the cover needs to be off the bulb for full effect of the UVB rays-- just make sure the bulb is a 10.0 the 5.0 HO will work but will need to go 8-10 inches from the basking spot--
this lighting is crucial for the over all health of the dragon--
Karrie

 

[Gormagon]

What I am seeing is a twin T8 fixture, right?

If so You will have to either remove the screen top OR somehow get it under the screen because screen mesh tops will reduce UVB rays by 40% to 50% of an already weak bulb if it is a 10.0. In optimum conditions your dragon has to get between 6 and, 8 inches of the "unobstructed bulbs to get any good UVB from it.
The Reptisun T5 HO 10.0 would be best in this situation because you can order one to fit inside (under the screen) with their low profile and, high output of UVB rays. Unobstructed distance of 10 to 16 inches, obstructed by the mesh would be around 8 to 10 inches distance (Maybe... not sure).