- Below is a website with a photo of this “Ursa Magister Fecit” stone relief with the "Ursa Magister" name inscribed.

- I would think it would be safe to put "ウルスス・マジスター作" rather than to translate the name into Japanese because it is says that it is the "first time in the western history an art piece is signed by the author."

http://www.djibnet.com/photo/s.pietro in valle/ursus-magiste...
Detail of the stone altar inside the S.Pietro in valle abbey (VI sec). Note the Ursus Magester Feci sign: first time in the western history an art piece is signed by the author.

Just for additional information:
http://www.24hourcampfire.com/rare_bears.html
THE SOUTHERN CALIFORNIA grizzly (Ursus magister) flutters on the California state flag but roams free nowhere as far as anybody knows.

And, the definition of the word "fecit"
http://www.babylon.com/definition/fecit/English
fecit
v. (Latin) "he made it", "she made it" (sometimes written on artwork along with the artist's name)

http://borealoarctos.blogspot.com/2009_08_01_archive.html
一方，URSIDAはラテン語の「ursus（ウルスス）」＝「熊」を語根化[urs-]し，接尾辞[-ida]をつけたもの．[-ida]は「（動物の）小目」を示すらしいのですが，辞典などにはまったく記載がなく，自信がありません．．



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Note added at 22 hrs (2010-06-25 13:54:52 GMT)
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The first website with the photo that I provided above is a close-up with the Ursus Magister (Magester) name carved in stone. Here is a website with the larger picture:
http://www.essential-architecture.com/STYLE/STY-035.htm
The photograph below is a Lombard marble altar closure slab of Magister Ursus, in honor of Duke Ilderic of Spoleto, 8th century, from Ferentillo, S. Pietro in Valle. Observe the Morning Star symbol placed in several locations on the marble altar.

Here is says Magister Ursus was commissioned to do the work. So, it is the name of the artist. Probably in Latin, it is reversed:
So, it can be マジスター・ウルスス作　(Like: 田中ケイコ versus ケイコ田中)
http://www.archive.org/stream/cathedralbuilder00scotuoft/cat...
In the museum of Verona is a precious fragment of
Comacine work dating from Luitprand's time. It was a
ciborium which Magister Ursus was commissioned to
make for the church of S. Giorgio di Valpolicella. It is
especially valuable as the first dated piece of sculpture of
the Longobardic era, and the first signed specimen of
Comacine interlaced work.