The Insects of the "Danmark" Expedition. 63^ 



2nd to the 5tli segment, on the front and hind margins of the 6th, 

 7th and 8th segment^ and only on the hind margins of the 9th to 

 the 11th segments. All the spines on the front margins are directed 

 backwards and all those on the hind margins forwards. The spines 

 are largest on the front segments, decrease in size backwards and 

 again become a little larger on the last segments; on the 2nd to the 

 4th segment they are in fairly regular straight rows, but on the 5ih 

 and following segment in shorter and somewhat curved rows. On 

 the anal joint there is a broad girdle of spines which are directed 

 forwards and placed in regular little rows. 



On the head there is a pair of sense-organs, each of which bears 

 two papillae, almost of the same size; the one has at the lip a clear, 

 refracting body and the other some sense processes. 



The mouth-hooks (fig. 11a) are broad and strong, not much bent; 

 the inner side with an obtuse tooth at the middle, the base with a 

 broad and strong, spine-like prolongation anteriorly, and posteriorly 

 there is a somewhat more slender spine directed backwards. The 

 mouth-hooks are jointed on the front pharyngeal plaies (fig. lib); 

 these plates are broadest anteriorly and the upper margin straight. 

 They are connected by means of a joint with the posterior part of 

 the pharyngeal skeleton, which consists on each side of an upper 

 (fig. lie) and a lower pharyngeal plate (fig. lid); the upper is the 

 larger, the upper margin straight, drawn out anteriorly into an 

 abruptly truncated, short prolongation. The posterior margin of the 

 pharyngeal plate is evenly rounded. The lower pharyngeal plate is 

 shorter than the upper, broadest posteriorly and here sharply incised. 



The anterior spiracles (fig. 12) occur in the articulation between 

 the second and third joint; the atrium is elongated and curved; the 

 base broad; at the tip there are five, short-stalked branches placed 

 in a line, those lying innermost being the largest. 



The posterior spiracles (fig. 13) are situated in the flattened hind 

 end of the body, somewhat up towards the dorsal surface; they are 

 surrounded by a broad, black ring of chitin which sends bridges in 

 over the spiracle; the one bridge is cleft at the tip. The bridges 

 reach almost to the tracheal opening, which lies inside the chitinous 

 ring. The spiracle is divided by the bridges into 3 parts, each 

 bearing an elongated respiratory-area, the middle one of which is 

 the shortest. 



The anus lies on the ven Irai side at a fair distance from the 

 hind end. 



The piiparium is ca. 9 mm. long and ca. 3 mm. broad, oval with 



' On the liind margin of tlie .')th segment there are a few spines. 



