potamogetonace^e. 249 



1, 3, 4, 5, 6. In the river Cam throughout the county. 

 — 1. Wilbraham Fen. — 4. Waterbeach Fen. River Ouse, 

 near Swavesey. Pits near the Observatory. — 5. Wicken Fen. 

 — 6. Aldreth. By Quaveney Drove, Stuntney; N. — 7. Ver- 

 muden's Drain, Chatteris. — 8. "Wisbech; J. B. 



5. P. prseldngus "Wul£ 



Bot. Gaz. i. 276. 



First noticed by C. C. B. in 1849. 



Streams and ditches. P. June. 



1. Often found floating down the river. — 3. In the river 

 just above Sheep's Green, Cambridge. — 4. In the ballast-pits > 

 near the railway junction at Chesterton ; Rev. Dr Cookson. 

 —5. Baitsbite.— 6. Roswell Pits, Ely. By Sandy's Cut; N. 



6. P. perfoliatus Linn. 



R. C. 124. M. M. 16. M. PI. 4. Relh. 67. 



Streams and ditches. P. July. 



1, 3, 4, 5, 6. In the river Cam throughout the county. — 

 4. Old Ouse, near Aldreth Bridge. Ouse, near Swavesey. 

 —5. Swaffham!; EL— 6. Roswell Pits, Ely. Witcham. 

 By Quaveney Drove, Stuntney ; N". — 7. Vermuden's Drain, 

 Chatteris. 



7. P. crispus Linn. Water Caltrops. Frog's Lettuce. 



Trihulus aquaticus minor quercus floribus Clusii, R. C. 

 165. P. seu Fontalis crispa, M. M. 16. P. crispum, M. PI. 

 4. Relh. 68. 



Ditches and pits. P. June. 



1. Coldham's Common, Cambridge. Hinton. Fulboum. 

 Brinkley. "West Wratting. Little Linton. — 2. Peat-holes, 

 Triplpw. — 3. Sheep's Green, Cambridge. Arlington. Great 

 Eversden. Croydon. Barton. Gamlingay. Toft. Tad- 



