The so-called Christian lamps in Terra Sigillata Africana (TSA) have been classified by Hayes into two major types, I and II. He has distinguished two classes in his type II, according to geographic place of manufacture or origin. Subtype II A groups lamps from central Tunisia characterized by a fine clay, glossy light orange slip, and carefully executed decoration using a great number of neatly drawn shoulder motives. Subtype II B groups lamps from northern Tunisia characterized by a coarser clay, dull brick-red slip, and larger shoulder stamps of often blurred quality. Lamps of Hayes types I and II, initially produced in Tunisia only, were broadly exported, then imitated throughout the Roman Empire for three centuries; consequently, they are extremely numerous. Several typologies have been worked out, but so far none is totally satisfactory, for new series continue to be distinguished. The basic work is the classification given in Atlante I, pp. 200–204, by Anselmino and Pavolini. More recently, Bonifay has devised a chronological typology that attempts simultaneously to take into account the shape, the decor, and the fabric (Bonifay 2004a, p. 371; 2005, pp. 34–37). This new approach, which leads him to individualize five groups—C 1 to C 5—is worthy but may seem premature, for very few methodical excavations of pottery workshops or kilns have been conducted in Tunisia. A major English-Tunisian field survey carried out in the 1980s in a large part of the Sahel located several important potteries and collected many thousands of ceramic sherds. But, unfortunately, so far only a short preliminary report has been published (Peacock, Bejaoui, and Ben Lazreg 1990). It is highly probable that new series or even subtypes of lamps will appear when the ceramic collected is thoroughly studied. Mackensen’s superb field survey in El Mahrine has revealed several series of Hayes type I lamps that had been totally unknown up until then (Mackensen 1993).
In his classification, Bonifay rightly takes into account the choice and the display of the stamped motifs on the lamp shoulders, but so far no comprehensive repertory of these stamps exists. Bussière 2007 has published the most extensive catalogue to date of lamp stamps; a planned larger work was hindered by insufficient Tunisian cooperation: he was not allowed free access to unpublished collections. The stamps found on the Getty lamps will be identified according to Barbera and Petriaggi’s stamp repertory from the Museo Nazionale Romano (MNR), which lists them all except one (MNR, pls. 11–31, pp. 399–419; for the exception, see Bussière 2007, no. Y 17, pl. 141). From their catalogue we also borrow the dates they attribute to the MNR lamps, whenever possible. Most often the dates are established by the stamps, following the chronology elaborated by Hayes and reproduced in Atlante I (Hayes 1972; Atlante I, pls. 56–138).
All the Getty lamps except cat. 500 belong to Hayes type II A and to Bonifay’s group C 2, meaning that they presumably come from central Tunisia. Cat. 500, of Hayes type II B, derives from northern Tunisia. The discus decors of the Getty lamps have published parallels, except perhaps cat. 498 (geometric rosette) and cat. 494 (seven apostles’ heads; similar heads are known, but on shoulders only). Among the decors already known: cat. 492 Christ treading on the snake and the lion; cat. 493 apostle or martyr; cat. 495 Chi-Rho monogram; cat. 496 cross-monogram; cat. 497 dromedary; cat. 499 geometrical motif; and cat. 500 dog.
All the bases of the Getty lamps consist of a raised ring connected to the handle, forming a design that is sometimes called a patera. In the middle of the base are two thin concentric circles, except on cat. 500, which instead has a workshop mark already recorded: a stylized anchor or spearhead (see MNR, p. 152, base type II.3.2; or Rosenthal and Sivan 1978, p. 68, no. 279, on Hayes type I examples).
The Getty lamps of the types here considered all date to the fifth or sixth century A.D., with the exception of cat. 492.