ORIGIN AND RADIATION 3 



the maxillae; the first three pairs were broad with scraping spines 

 at the tip, while the others each had two flaps and resembled the 

 swimming legs of modern copepods (p. 7). The female carried an 

 e gg pouch on the underside of the body behind the legs. Lcpidocaris 

 is clearly a crustacean, and further, it can be classified as a member 

 of the sub class Branchiopoda. 



The Branchiopoda can be divided into various sub groups, and 

 of these the Anostraca (fig. 2) show the greatest resemblance to 

 Lepidocaris. They have narrow tapering bodies, with nineteen or 

 more segments, and eleven, sometimes more pairs of legs. The 

 maxillae are small, and the females carry their eggs in a pouch 

 behind the legs. But there are also some differences. The Anostraca 

 have stalked eyes, while no eyes were found in Lepidocaris. The 



HOOK FO*. MALC 

 OMMX) 



£CCS IN 6H0C0 

 POUCH 



MUSCltS WHICH OPtN 

 BROOD POUCH TO 



PCLg/ise eacs 



Fig. 1. Artemia salina (Anostraca), lateral view of female in the 



normal swimming position, with the back downwards. Actual 



length about 1 cm. Drawn from a specimen of the Californian 



stock reared in sea water. 



male anostracan has the antennae, not the first maxillae, modified 

 to form clasping organs, and the antennae of the female are not 

 branched or used for swimming. In spite of such differences the 

 similarities are great enough for Lepidocaris to be regarded as near 

 to the stock from which the Anostraca arose. Unfortunately the 

 Anostraca, although much larger than Lepidocaris, have very 

 delicate skeletons and have not often been preserved as fossils. Such 

 fossils as have been found do not help much with tracing the 

 evolution of the group. 



The other members of the Branchiopoda differ markedly from 

 Lepidocaris and the Anostraca by having a carapace. This is a 

 flap projecting from the back of the head and covering the body 

 to a varying extent. In the Conchostraca the whole body and the 

 limbs are enclosed within the carapace, which extends downwards 



