I was consulting my reference books on trilobites last night, storing up jargon for future posts. Allow me to share with you this classic collop of scientific prose at its most high falutin', extracted from E.N.K. Clarkson's Invertebrate Paleontology and Evolution:
Also to be found in post-Cambrian stocks, notably the Family Asaphidae, are small protuberances on the inner faces of the thoricac doublures, which presuming acted as stops preventing overgliding of the pleura as they came to rest during enrollment. These are the organs of Pander; they are not to be confused with panderian openings which, though similarly located, probably were the orifices of some kind of segmented and possibly excretory organs.