HANSEN AND SÖRENSEN, THE TARTARIDES. 29 



Mandihular polyps are folded in the vertical plane; the tihial qxirt 

 without any terminal process; the tarsal ^oart at the hase 

 nearly as hroad and äeep as the end of the tihial part, 

 shajied ahout as a truncate cone and terminating in a well- 

 developed movable clair: a chela is therefore not formed. 



Cox£e of the first pair of walking legs with their lower surface 

 nearly in the same plane as that of the following pairs 

 and not liigher than that of the mandibles; they are 

 evidently longer than. and more than half as broad as, 

 the following coxae. 



T ar sus of the first pair of walking legs six-jointed, from only 

 a little longer than to scarcely ttcice as long as metatarsns. 



Coxae of the second pair of walking legs with a slender acute 

 process from the distal inner (anterior) angle. 



Metatarsns of the three posterior pairs of walking legs long, 

 almost as long as tibia and longer than the whole tarsus. 



Only one pair of lungs, belonging to the second abdominal seg- 

 ment: the spirades visible from the outside. The trunk 

 of each lung moderately long with the lower ivall about as 

 long as the spirade; the margins of the tracheal »pouches» 

 scarcely more chitinized than their walls. 



(Sexual differences at least marked by the structure of the 

 flagellum and second to fourth abdominal sternites.) 



IV. On some Interpretations of Structural 

 Features. 



We think it necessary to produce some remarks in order 

 to explain some of the interpretations, given in the preceding 

 chapter, and the differences between these and various state- 

 ments in the literature. 



The two small plates constituting the firmly chitinized 

 dorsal elements of the first thoracic segment ha ve been over- 

 looked by Cambridge, Thorell, Kraépelin and Pocock. In the 

 rich material investigated by us we found this structure 

 essentially identical, the plates in question differing only a 

 little in shape. These plates were seen and drawn by Cook 

 in liis presumed new genus Hiihbardia, but he did not under- 

 stand their significance as the dorsal part of a separate thoracic 

 segment; furthermore as these plates in his opinion were not 



l^. 



