THE GENERA AND SPECIES OF SYMPHYLA. 55 



and claws ; the distal seta on the tibia as long as the depth 

 of the metatarsus; this last joint with three dorsal setis, and 

 the distal one of these somewhat longer than the others^ but 

 only a little more than half as long as the depth of the joint; 

 the tarsus with four dorsal setfe in the anterior row; the 

 anterior claw (fig. 3/) is rather short and robust, rather 

 curved, and only a little longer than the posterior claw, 

 which is somewhat more slender but scarcely more cnrved 

 than the other. The first pair of legs with the anterior claw 

 (fig. 3 g) rather short and robust, the posterior claw much 

 more slender and nearly two thirds as long as the other, and 

 both claws are moderately curved. The cerci (fig. 3 h) 

 slightly more than three and a half times longer than deep, 

 and the sette somewhat more numerous than in the typical 

 form. The experience as to the degree and quality of the 

 variation of Scut, immaculata (Newp.) in Europe has 

 taught me that the animals described hero must be con- 

 sidered as a variety of Scut, angulosa, the most essential 

 diiferences between the typical form and the variety being 

 the claws on the posterior legs and the sense-organs on the 

 terminal joint of the antennjB. 



Locality. — The southern thii-d of South America, in 

 various localities : Monte Buenos Aires, in Gobern, S. Cruz, 

 southern Patagonia, five specimens, among which are the 

 largest specimens examined; Porto Piramides, Chubut, 

 Patagonia, the two specimens described as the variety 

 brevicornis; S. Pedro, Misiones, Argentina, a typical 

 specimen with the full number of legs, but measuring only 

 2*4 mm. in length ; Posadas, ]\Iisiones, Argentina, the 

 immature specimen of which the posterior pair of legs have 

 been mentioned above and shown in fig. 2 h ; Salto, in 

 Uruguay, two small, immature specimens. All specimens 

 have been captured by Dr. F. Silvestri. 



E, em arks. — The species is easily recognised from all 

 other forms of the genus by the shape of the second scutum, 

 together with the number and length of its outwards-directed 

 seta) and the well-developed exopods at the posterior legs. 



