The Scottish Naturalist. 



3°5 



First family— HYDROPHILID.E (17 genera.) 



1. An. with at least 7 js. Fr. of clyp. not emarginate 



- - only 6 js. Fr. of h. deeply emarginate 



2. Th. broader at ba. than in fr. ; its surface without 



consp. furrows or ridges. Less than 5 1. 



'; More than 1. 



Not as above ..... 



3. H. -b. consisting of more than 4 dist. segs. 



- - - only 4 dist. segs. [Not more than 1 1. A str 

 close to sut. in hi. part of e. is obs. in fr. An. 9 j 

 Pal. short] .... 



4. Last j. of pal. longer than pen. 



- - - - shorter than pen. An. 9 j. 

 Last 2 js. of pal. equal. Sut. str. as above (see 



Chcetarthria). An. 9 j. 



5. Sut. str. as above. More than 2 1. An. 9 j. 



- - - -. Less than 2 1. An. 9 j. 



- - either absent, or entire. An. S j. 

 ■6. Th. very finely and rather ind. punc. Space between 



ins. of mid. and hi. legs flat . 



- strongly and roughly punc. Space between ins. of 

 mid. and hi. legs elev. 



7. E. not deeply p. -s. .... 



- deeply p. -s. . 

 "8. Pal. dist. longer than tar. of mid. legs. 



- not dist. longer than tar. of mid. legs 

 9. Ap. j. of pal. not more than ]4. as long as 2nd. Sut 



str. as in CJmtarthria. Space between ins. of mid 

 and hi. legs elev. .... 



- - - - more than y 2 as long as 2nd. Sut. str. obs 

 Space between ins. of mid. and hi. legs flat 



10. Sc. more than y 2 as long as th. An. 9 j. 



- hardly \ as long as th. An. 9 j. 



11. Last j. of pal. cons, longer than pen. . 

 Pen. j. of the rather short pal. large and thick. Last 



j. much shorter and thinner. An. 9 j. 



Pal. cons, shorter than h. and th. 



- about as long as h. and th. An. 9 j. 

 Th. strongly tr. An. 9 j. 



- hardly (or not) tr. An. 7 j. 



12 



*3 



Spercheus 



3 

 10 



11 



4 



Chsetarthria 



5 

 9 



Enochrus 



Hydrobius 



6 



7 



Anacama 



Paracymus 



8 



Berosus 



Limnebius 



Laccobius 



Philhydrus 



Helochares 



1 1 ydrophilus 



Hydrous 



12 



Ochthebius 



13 



Hydrama 



Helophorus 

 Hydrochus 



Hydrophilus. 



Smooth, shining. Pit. b. An., pal., and some fringes 

 of hair on the legs, more or less r. E. with 4 rows 

 of puncs. ; a spine at ap. Ap. j. of ant. tar. 

 of 6 strongly dil. 18 1. E. . 



piceus 



