THE TETTIGID2E OF CEYLON. 
101 
p. 214) on the aquatic habits of Scelimena gavialis , Sauss. (Plate 
I., fig. 4), there is in Oeylon “ a large group of aquatic Acridians 
of the family Tettigidae, e.g ., Scelimena (harpago) gavialis Sauss., 
and allied species. This species in particular has the hind tibia 
and tarsus laterally expanded for swimming. The insects frequent 
the mountain streams of Ceylon, resting on the wet rocks in mid 
stream. When disturbed they leap without hesitation into the 
water, and either swim to another rock or dive to the bottom, often 
remaining there for a considerable period.” The author then states 
that he remembers “ on one occasion observing the larva of a Tettix 
walking about among the dead leaves at the bottom of a shallow 
pool.” Lastly he states that Grcivialidium crocodilus , De Sauss., is 
another species that frequents wet rocks ; though he has never 
seen this insect actually take to the water. According to Bolivar 
(1887) Capt. Boys and Westwood have recorded similar amphibious 
habits in Scelimena , and similarly Sharp (1895) reiterates observa¬ 
tions, probably by these authors, on the Ceylon and Himalayan 
species. De Saussure (1860, p. 481) likewise narrates the follow¬ 
ing observations made by M. A. Humbert, who was then keeper of 
the Museum of Geneva :— 
“The species of Scelimena live upon the borders of rivulets and 
ponds. They post themselves upon the rocks and frequently dart 
out upon the water leaping and fluttering by means of their large 
membranous wings. They poise on the water without becoming 
wet, and then in clearing the surface use their wings again. 
“This ability of taking the water as a point of departure un¬ 
doubtedly is due to the dilatation of the first joint of the posterior 
tarsi which has been observed among these species. These insects 
appear moreover to have no fear of immersing themselves 
completely. They jump into the water as well as upon the surface, 
and it is probable that their posterior tibiae, membranous at the 
borders, and the first joint of the posterior tarsi, when it is 
enlarged, perform the function of fins. Finally the species of 
Scelimena also like to refresh themselves in the tiny streams of 
water which glide along the rocks. One often finds them firmly 
clinging to a rock and entirely submerged by the current of water, 
apparently taking a bath. These habits have been observed 
equally in both Scelimena crocodilus and Scelimena gavialis .” 
An allied competitor in the racial struggle, Scelimena logani 
(plate I., fig. 5), probably displays similar or even more pro¬ 
nounced amphibious tendencies, as evidenced in the very widely 
laminate expanded margins of the posterior tibiae, which are 
formed into perfect paddles for swimming. It was found fre¬ 
quenting a rocky stream and also living on rocks and in the water 
