18 H. J. HANSEN. 



with caustic potash ; the dorsal part of the head and of the 

 two anterior segments of the trunk has been cut off and the 

 lower half put in a cold solution of about 25 per cent., in 

 which it remained during twenty-four hours, and was then 

 put in glycerine on an object-glass. The hypopharyux and 

 the maxillulge have also been examined by dissection of a 

 head directly taken out of the spirit. The following descrip- 

 tion is founded almost exclusively on Scutig. immaculata; 

 some smaller differences between the structure of this species 

 and of Scolop. vulgaris have been observed, but, with the 

 exception of one point, I did not find it necessary to mention 

 them. 



The mandibles are tvvo-jointed as in typical Diplopods, 

 but the interpretation of this curious fact must be postponed, 

 and shall be dealt with in a paper on the morphology of the 

 skeleton of some classes of Arthropods. The basal joint 

 (Pi. 1, fig. 1 a, a.) is narrow when seen from below, but rather 

 broad when seen from the outer side ; to the upper margin 

 just behind the middle a strong muscle {h.) is attached. The 

 distal joint (c.) is strongly compressed, its articulation on the 

 basal joint is well developed, and besides, it has on the upper 

 side near the basal margin a strongly prominent part, which 

 seems to be a secondary condylus, a structure difficult to 

 understand. The oblique distal cutting edge is serrated with 

 a moderately deep incision at the middle ; in this incision is 

 found a rather small, thin lacinia (tig. 1 c, I.), articulated to 

 the upper surface of the mandible near the margin of the 

 incision ; this lacinia is distally very irregularly and partly 

 deeply serrated, and has, besides, a narrow, nearly setiform 

 pi'ocess, directed inwards above the adjacent part of the 

 mandible ; this lacinia is equally developed both on the right 

 and on the left mandible. To the inner posterior angle of 

 the second joint of the mandible a tendon of a very strong 

 muscle {d.) is attached. 



The max i Ike (c.) are quite independent of the labiun), 

 united with it only by a belt of articulating membrane. The 

 ''stipes" is long; posteriorly it is bent upwards and ter- 



