[2] Four separate commercial shipbuilders were involved in their construction by contract - including André-François Normand, Courtois and Denise at Honfleur, and Fouache at Le Havre (two ships), while the sixth vessel was built by Pierre Ozanne at Cherbourg Dockyard.

The vessels were flush-decked and originally designed to carry a 12-inch mortar.

However, as the British navy captured Etna within a year and a half of her launch at which time she was not carrying any mortar, it is possible that the design was modified quite early to delete the mortar.

[2] The Royal Navy captured three of the six vessels in the class.

Three members of the class (including two in Royal Navy service), were lost to wrecking or grounding.