94: GEO. H. HORN, M. D. 



give still greater firmness. Trachypachys has the coxae as mobile as in 

 ordinary Carabidae, there is however but a short line of median contact. 



With the above notes and the characters already well known in the 

 books an arrangement of the Adephagous families may be outlined in 

 the following manner : 



Metasternum with an ante-coxal piece, separated by a well marked 

 suture, reaching from one side to the other and extending 

 in a triangular process between the coxae. 

 Antennae eleven-jointed. Posterior coxae mobile and simple. Habits 

 terrestrial. 

 Antennae inserted on the front above the base of the mandibles. 



CICINDELIDiE. 

 Antennae arising at the side of the head between the base of the 



mandibles and the eyes CARABID.^. 



Antennaj ten-jointed. Posterior coxae fixed and with large plates 

 almost entirely concealing the abdomen. Habits aquatic. 



HALIPLID^. 

 Metasternum with a very short ante-coxal piece, the suture indistinct, 

 posteriorly not prolonged between the coxae. Habits aquatic. 

 Legs ambulatorial. Anterior coxae globular. 



AMPHIZOIDiE. 



Legs natatorial. Anterior coxag conical. . PELOBIID.^. 



Metasternum prolonged behind in a triangular process, the ante-coxal 



piece entirely wanting. Habits aquatic. 



xlntennae slender, filiform or setaceous. Abdomen with six segments. 



Eyes two. DYTISCIDiE. 



Antennse irregular, very short. Abdomen with seven segments, the 

 first two closely united. Eyes four. . . GYRINID>ffi. 



The above scheme seems to give a division of families in accord with 

 both structure and habits. I have used the expression "aquatic" in 

 order that Amphizoa might be accommodated, its habits, while sub- 

 a(iuatic, are by no means " natatorial." I have already given a sufii- 

 ciently full account of the habits of this remarkable insect, (Proc. Ent. 

 Soc. Phil, vi, p. 289), and will merely add in brief that it acts precisely 

 like the Parnida? and is equally poor as a swimmer, and a very awkward 

 walker out of the water. 



The Cicindelidaj, with the exception of a few genera, have the maxillae 

 armed at tip with a movable hook. This is peculiar to the family. For 

 many years the books have presented Trignnodacfyla of the Carabidae 

 as an exception and an articulated hook assigned to it. In the discussion 



