frontage of a consular army

[Justin Swanton]

Caesar commonly mentions, as do many others the raising of 'Legions'.  You are happy that these 'lighter-armed' troops are an integral part of his army - but we never see them raised or otherwise mentioned.

It's possible that these 'lightly armed foot' were legionaries who discarded their regular arms and armour and carried only light equipment in order be fast and mobile for the special role they had to fulfill. Or they were Auxilia-type non-Romans. Or a part of the regular Roman establishment that were separate from the legions. Theories... The point is that we never seem them operating as part of a legion in the way the leves and velites did.

In addition, we do have subjective evidence that the velites (from an earlier comment) are indeed a part of the heavy infantry contubernium structure.  Firstly, they are specifically apportioned across the maniples at a ratio of 2:6.  Then they are not mentioned in the description of the camp and have no separate areas for their, presumed, tents; and the proportions of the camping exactly allow for them to be incorporated into the maniples of the heavy infantry.

There is, indeed, absolutely no reason not to think that the contubernium was 8 in c300BCE and wasn't still, perhaps, 700 years later!

The only detailed descriptions we have of the contubernium are from Hyginus and Vegetius, and it's clear in both cases they are talking about the Marian and post-Marian legion. There's an interesting thread on this at the SoA forum. See here. (I can rehash the main points if you like) Which means it probably postdates the disappearance of the velites, last mentioned in Marius' campaign against Jugurtha.