CHAPTER VIII 



THE SYNCARIDA 



Division Syncarida, Packard (1886). 

 Order Anaspidacea. 



Definition. — To the characters mentioned on y>- 148 as distinctive 

 of the Division, the following may be added : Thoracic limbs 

 with exopodites (except the last, or the last two pairs), and with 

 a double series of lamellar epipodites attached to the outer side 

 of the coxopodites (except the last pair) ; the first pair may have 

 gnathobasic endites on the coxopodite ; pleopoda with the endo- 

 podite reduced or absent except in the first two pairs in the male 

 sex ; uropods lamellar, forming, with the telson, a tail -fan ; a 

 statocyst is present in the basal segment of the antennules. 



Historical. — Anasjndes tasmaniae was first described by G. M. 

 Thomson in 1892, and more fully in 1894. He placed it among 

 the " Schizopoda," establishing for it the family Anaspidae. In 

 1897 the present writer discussed some points in its morphology 

 and called attention to its resemblance to certain fossil Crustacea 

 for which Packard had established the group Syncarida. In 1904 

 Grobben (in iiis edition of Claus's Lehrbuch der Zoologie) referred 

 Anaspides to a new subdivision of the Malacostraca Avhich he 

 termed Anomostraca, and in the same year the system of classifica- 

 tion adopted here was published. Quite recently a new and very 

 remarkable representative of the Syncarida has been discovered 

 and described by Mr. 0. A. Sayce under the name Koonunga cursor. 

 It has been suggested that Bathynella natans, described by Vejdovsky 

 in 1882, also belongs to this group, but our knowledge of the 

 structure of this minute form is still very imperfect. 



Morphology. 



The body, in the living Syncarida, is elongated and sub- 

 cylindrical, with all the trunk -somites distinct from each other. 

 In Anaspides (Fig. 94) the anterior limit of the first thoracic 



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