ough on all fours. No plausible suggestion has been offered as to the
purpose of these mysterious burrows, which cannot fail to remind us of
the labyrinth which, according to Varro's description as quoted by Pliny
(_Hist. Nat._ lib. xxxvi. c. 19, S 4), was the distinguishing mark of
Porsena's tomb, and which have led some adventurous archaeologists to
identify this sepulchre with that of the great king of Etruria (Dennis,
_u.s._, pp. 393 ff.). (E. V.; O. M. D.)

[Illustration: Fig. 25.--Plan of a portion of the principal storey in
the Poggio Gajella. (From Dennis.)]

_Modern Discoveries_.--In 1873 was discovered, near the cemetery of St
Domitilla, the semi-subterranean basilica of Santi Nereo ed Achilleo,
100 ft. by 60 ft. This is now covered with a roof, and the fallen
columns have been raised up. The lower part of a pillar, which once
supported a baldachino over the altar, still preserves the name
ACILLEUS, and beneath it a bas-relief of the martyr, with his hands
bound, receiving his death-blow from the executioner. The base of a
similar column has only feet in the same attitude, and probably bore the
name NEREUS. In a grave in the apse was found a large fragment of an
inscription, composed by Pope Damasus, but set up by his successor
Siricius, which, from the note-book of a Salzburg pilgrim of the 8th
century, can be completed thus:--

------
Militiae nomen dederant saevum / Q \ ue gerebant
Officium pariter spectantes juss | AIYR \ anni
Praeceptis pulsante metu servi | RE PAR \ ati
Mira fides rerum subito posue | RE FVRORE \ m
Conversi fugiunt ducis impia castr | A RELINQVVNI \
Projiciunt clypeos faleras tel | AQ. CRVENIA |
Confessi gaudent Christi portar | E IRIVMFOS |
Credite per Damasum possit quid | GLORIA CHRISTI |
------------------

Nereus (see Rom. xvi. 15) and Achilleus, said to have been baptized by
St Peter, refused to do the bidding of Domitian as praetorians, and
entering the service of Flavia Domitilla, suffered martyrdom with their
mistress Petronilla, of the Aurelian family closely connected with the
Flavii, and the spiritual daughter of St Peter, who was buried in a
sarcophagus with the inscription:--

AVRELIAE . PETRONILLAE . FIL . DVLCISSIMAE

This is now in St Peter's, but was probably originally behind the apse
of this basilica, for there is a