POTAMOGETONACE.E. 251 



11. P. pectinatus Linn. 



Millefolium tenuifolium, R. C. 99. P. millefolium seu 

 folii's gramineis ramosum, M. M. 1 6. P. pectinatum, M. PI. 

 4. Relh. 69. P. marinum, Relh. ed. 1, Suppl. ii. 9. 



Ponds and streams. P. June, July. 



3. Harston ; N". — 4. In the river near Chesterton. 

 "Waterbeach. Old Ouse, near Aldreth Bridge. Eiver Ouse, 

 near Swavesey. — 5. Wicken Fen. Olayhythe. In Bottisham 

 Lode, near its mouth. — 6. Ely. Stretham Ferry ; J. M. — 

 7. Vermuden's Drain, Chatteris. — 8. Newton. In some pits 

 below Wisbech in 1787 I; Relh. 



[In all probability P. fiabellatus inhabits this county. 

 It grows in "Wick Fen, near Nordelph, Norfolk, which is 

 only about four miles from the boundary of Cambridge- 

 shire.] 



12. P. densus Linn. Small Water Caltrops. 



Tribulus aquaticus minor muscadellce floribus, R. C. 1 65. 

 P. seu Fontalis media lueens, M. M. 16. P. densurn, Relh. 

 68. 



Ditches. P. June, July. 



Common, except (?) in the Fens. There are no recorded 

 stations for it in the (7) Chatteris, nor (8) Wisbech Districts. 



Ruppia Linn. 



1. E. rostell^ta Koch. Tassel Pond-weed. 



R. maritima, Relh. ed. 2, 66 ; ed. 3, 70. 

 Salt marshes. July, August. 



8. Ditches below Wisbech; Mr Skrimshire. It is proba- 

 ble that this was R. rostellata. 



