14 H. J. HANSEN. 



histological structure lias not been undertaken. In two 

 other species, vScut. crassicornis, n. sp., and Scut, 

 pauperata, u. sp., a deep depression is found, but no 

 invagination, and therefore no cavity, has been developed ; 

 the interior tissue shows an organ less distinct than in 

 Scut, immaculata. In the other species of Scutigcrella a 

 feeble and simple depression is observed; in Scolopendrella 

 the last scutum is simple. 



E. Legs. — The legs of the first pair will be treated 

 separately below. They present always essential structural 

 differences from the eleven other pairs, which in all main 

 points are similar to each other, not only in the same animal 

 but in all species of the order. These eleven pairs consist 

 apparently of five joints. But the proximal one of these 

 joints is, in my opinion, the trochanter, and the coxa can 

 easily be seen as a separate portion of the skeleton on the 

 lower surface of the trunk on a specimen cleaned with 

 caustic potash. That the second one of the five joints 

 mentioned is the femur and the last one is the tarsus is, of 

 course, certain, but the interpretation of the two remaining 

 joints is more dijSicult. The shape of these joints and the 

 presence of only one condylus placed on the dorsal side seem 

 to indicate that the joints must be interpreted as patella and 

 tibia; on the other hand, the essential movement between 

 the joints being a rather strong flexion in the vertical plane, 

 while the movement forwards and backwards around a sub- 

 vertical axis seems to be feeble, leads to the assumption 

 that the joints are respectively tibia and metatarsus. I 

 think that this last interpretation is correct, and it is 

 supported by the shape of the dorsal condylus, which is 

 unusually broad, and seems to be formed by a junction of two 

 condyli placed closely together. The tarsus terminates in a 

 prsetarsus ^ with two claws, which are never quite equal in 

 shape, the anterior claw being always broader, generally 



' This name lias been introduced by N. J. C. II. de Meijerc in liis paper 

 " Ueber das Ictzte Glied der Beine bei den Artliropodcn " (' Zoolof^. Jalir- 

 biicher, Abtheil. fur Analumic, etc.,' lid. \iv, 1901, jip. 117— '1-70, Taf. o(l— 37). 



