How to use Chitons in a sentence
The Chitons and their allies were placed under the Gastropoda, as a distinct branch called Isopleura, and for the Acephala de Blainville's name Lamellibranchia was substituted.
Among the Amphineura we find one pair of coelomic ducts in the Aplacophora, two pairs in the Chitons.
In the Chitons or Polyplacophora, on the other hand, the two cavities are separate, and there are independent genital ducts.
Originally the Chitons were placed with the limpets, Patella, in Cuvier's Cyclobranchia, an order of the Gastropoda.
In some species there are also sensory papillae comparable to the aesthetes of Chitons.Advertisement
It closely resembles in the early stages that of Chitons.
On this view then the Aplacophora are more primitive than the Polyplacophora in the relations of coelom, gonad and coelomoducts; and the genital ducts of the Chitons have arisen either by metameric repetition within the group, or by the gradual loss of an original connexion between the generative sac and the renal tube, as in Lamellibranchs and Gastropods, the generative sac acquiring a separate duct and opening to the exterior on each side.
The coelom differs from that of the Chitons in the fact that the cavities of the genital organs are continuous with it, and in the fact that there is only one pair of coelomoducts resembling the renal organs of Chitons, but serving also as genital ducts.
The aorta is not independent as in Chitons, but is a sinus like the other channels of the circulation.