358 



in the middle of the excision or else at the base of the anterior border of 

 the posterior tooth. The last two keels only very obscurely bidentate. 

 Copulatory foot different from that of the two preceding species in 

 that the lower process is much the shorter and thinner of the two 

 and is curved backwards from its base, while the superior process 

 is in its distal half curled completely on itself. 



Length about 54 mm.; width of 10 th somite 6; of l 8t 5.5, length 

 of I** 2.2. 



This species may be recognised at once from the two preceding 

 by the difference in the form of the two teeth of the keels, the posi- 

 tion of the pore and the form of the copulatory foot. 



Strongylosoma , Brandt. 



I include under this genus both Strongylosoma of Brandt and authors , 

 and the species of Paradesmus of the gracilis and coarctatus type. 

 There seems to be little besides the size of the keels to separate these 

 two so-called genera, but this is obviously a character which is sub- 

 ject to a large amount of specific variation within the limits of the 

 same genus. 



The species discussed in this paper present the following features 

 in common. The segments are either strongly or weakly keeled and 

 the pores are situated on the lateral margins of the keels towards 

 their posterior extremity. The I st segment is scarcely if at all keeled; 

 but the keel of the 2 nd is large and projects below the level of the 

 edge of the 1 st and of the keel of the 3 nd . The keel-bearing part of 

 the segments from the 5 th to about the l 8t is furnished with a trans- 

 verse groove lying between the bases of the keels; sometimes the 

 area is also marked more or less clearly by a longitudinal groove. The 

 tail is truncate and bitubercular apically and usually considerably bro- 

 ader at the base than at the distal end. The anal sternite is trian- 

 gular and bitubercular. The sternal areas conspicuous, the legs con- 

 sequently separated widely at the base. The femur (3 rd ) and tarsus 

 (6 th ) segments of the legs are the longest. Legs and antennae both 

 rather slender. There is frequently a crest above thé base of the legs , 

 especially in the anterior half of the body. 



The copulatory feet of the rf are entirely free at the base, being 

 unprotected by upgrowths of the sternal area which supports them; 



