A pain to do, this is the final mission on Easy Mode. There is a time limit, and on the fastest path there are no pickups aside from the bombs. Just as the mission description says, there are six bombs to disarm. If you follow this, you should finish with a fair amount of time on the clock.
Start off by equipping the machine gun. Run right and ignore the first door, instead proceeding to the second. The first leads to a gray raptor and an ammo pickup, but this mission is done faster and just as easily without picking up the ammunition.
The level's layout is a lot like Seek and Destroy and generally follows the same rules. Go right whenever possible and take the furthest away doors. There will be an exception, and this is when after you exit one door, you will want to run left and hop over 3 of the wave volcano things. This will again be repeated for three fire fissures not long after.
When you reach a very long corridor with not a lot of head room, this indicates the triceratops is in the area. Unlike Seek and destroy, you DO need to fight this one and, if you're impatient and believed it couldn't be killed, it can be. Before you do so, you must have picked up the four bombs from earlier sections of the volcano. If you have, excellent. If not, then you'll probably run out of time looking for them. Keep shooting at the triceratops, running away as needed and changing weapons (shotgun, then the small tranq. bazooka, then tranq. machine gun seems to work well and will save the rest of your lethal machine gun ammo) until it falls dead. Proceed right and make sure you have a lethal weapon equipped. Go through the door.
Keep going right, taking out Biosyn along the way. Grab the final two bombs and continue right until you see the mission start/mission end animation on Dr. Grant.
The mission debriefing says there is a malfunction in the bombs and they were unable to be disarmed. It also states you now have ammunition for your new weapon (most likely the large tranq. bazooka, as it had none before).
If you are on Easy, sit back and enjoy the game's ending. If you're on higher difficulties, well, prepare to keep playing.