The carina descends only just below the basal points of the terga, instead of far below them.
Hence we see how wonderfully variable the terga are in this genus.
The scuta and terga are much more elongated, a scutum being here 35/1000ths of an inch in length.
The terga of the somites may, in fact, be said to have become formed.
In the terga, the spur is about half the width of the whole valve, and therefore rather wider than in A. spongites.
The scuta, terga, and carina are much larger than the other valves.
From the protection afforded by the two terga to the dorso-lateral surface of the animal, these valves have been thus called.
The wings of Hexapoda are lateral expansions of the terga of the second and third thoracic somites.
All the valves, even in the same species, are subject to considerable variation in shape, more especially the terga.
Scuta.The scuta and carinal half of the terga are blueish-green.