82 PAPERS ON ZOOLOGY OF MICHIGAN. 



180. Dytiscus marginalis Linn. Two specimens found swimming in 

 the water of the bay, on the northeast shore, July 16. 



181. Dytiscus hyhridus Aube. One specimen found swimming in rock 

 pool, on the northeast shore, June 25. Six specimens found 

 crawling in wet sand at the edge of the water, on the northeast 

 shore, July 16. 



182. Dytiscus harristi Kirby. Two specimens found swimming in 

 rock pool, on the northeast shore, June 21. 



183. Acilius semisulcatus Aube. Two specimens taken in the rock 

 pools, on the northeast shore, June 21-22. Five found by dredg- 

 ing pond, July 17. 



184. Acilius fraternus Harr. Three specimens taken by dredging in 

 the pond, July 17. 



185. Graphoderus liberus Say. Ten specimens taken by dredging 

 pond, July 17. 



186. Ctjhister fimhriolatus Say. Two specimens found in the rock 

 pools, on the northeast shore, June 23. 



Gyrinidae. 



187. Gyriuus aeneolus Lee. One specimen found in a rock pool, on 

 the northeast shore, July 17. 



188. Gyrinus lugens Lee. Nine specimens found under boards and 

 debris at the edge of the water, on the northeast shore, Jul,y 17. 



189. Dineutes emarginatus Say. Six specimens found swimming on 

 the surface of the pond, July 17. Common. 



190. Dineutes hornii Roberts. Two specimens found in the rock pools, 

 on the northeast shore, June 23. 



191. Dineutes nigrior Roberts. Two specimens found swimming in 

 a rock pool, on the northeast shore, July 17. 



Hydrophilidae. 



192. Helophorus lacustris Lee. Three specimens found crawling under 

 wet debris near the edge of the water, on the northeast shore, 

 July 17. 



193. Helophorus lineatus Say. Two specimens taken on the wet sand 

 and two on a log, on the northeast shore, June 21-25. 



194. Helophorus tubercidatus Gyll. One specimen taken under de- 

 bris, on the northeast shore, July 17. 



195. Hydrochus excavatus Lee. One specimen found crawling on wet 

 rocks, on the northeast shore, June 21. 



196. Hydrophilus triangularis Say. One specimen taken in a rock 

 pool, on the northeast shore, July 17. 



