Injuries are taking a toll on the Jaguars' secondary. (US Presswire)

The Jaguars are already in the bottom third of the NFL in passing defense, giving up an average of 251.3 yards through the air per game. Their task of improving the pass defense isn't getting any easier with CBs Rashean Mathis (groin) and Derek Cox (back) missing practice on Thursday due to injuries, according to the Florida-Times Union

Mathis and Cox were both were limited participants on Wednesday, but their status is more up in the air after missing Thursday.

It's an unfortunate time to be dealing with injuries in the secondary with the Detroit Lions coming to town this weekend. Led by QB Matthew Stafford and WR Calvin Johnson, the Lions rank second in the NFL with 310.4 passing yards per game. 

S Dwight Lowery (ankle) has been ruled out for Sunday. That could leave a starting secondary of CBs Aaron Ross and William Middleton along with Dawan Landry and Chris Prosinski starting at S -- not exactly a lineup the Jaguars can feel great about this weekend.

In better injury news, WR Laurent Robinson (concussion) has returned to the practice field and is looking more and more likely to return after missing all of October.

WR Armstrong added: The Jaguars are still tinkering with their roster after dealing WR Mike Thomas to the Detroit Lions for a 2014 fifth-round draft pick earlier this week. 

To replace Thomas on the roster, the Jaguars have claimed fourth-year WR Anthony Armstrong off of waivers from the Miami Dolphins. Armstrong (5-11, 180) has 54 career receptions for 986 yards and five TDs. He appeared in five games for the Dolphins this season (3 receptions, 12 yards) after the Washington Redskins cut him in the preseason.

Britton staying ready: Adjusting from the starting lineup to the bench has been tough for LG Eben Britton, who was replaced two weeks ago by rookie Michael Brewster. The former second-round draft pick told the Florida-Times Union that he's never been benched in his career, but he's trying to remain positive and ready.

“It was hard,” he said. “But you have to be ready at any moment and know your stuff better than anybody else. That’s the way you have to approach the situation. … You can’t always see what the reason might be, but you have to play the cards you’re dealt and play them well.”

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