Mr. J. Ralfs on the British species of Grammonema. 457 



Some years since Mr. Waterhouse fii'st discovered this insect 

 near Dorking. I found it at IMickleham rather plentifully the 

 beginning of October 1837, on herbage under the hedges, in the 

 park behind the church; at Gravesend in June, Mr. S. Stevens : 

 it appears to be confined to chalky districts. 



34. A. atomarium, Kirb., Gyll., Germ., Steph. Man., Schonh. 



— pusillum, Germ. 



This is the most minute species of the genus found in England ; 

 it was originally described by Mr. Khby from a Swedish speci- 

 men sent him by Major Gyllenhal, and for many years it was un- 

 known as a British insect until Mr. Waterhouse found it near 

 Dorking. In a note from Germar relative to this species, he in- 

 forms me that the " Ap. atomarium of Kirby is, without doubt, 

 identical mth the Ap. pusillum of Germar." 



Taken in abundance at Birch Wood on the wild thyme {Thy- 

 mus Serpyllum) in September by Mr. S. Stevens, Mr. Smith and 

 myself, and occasionally in other places on the same plant. 



35. A. vicinum, Kirb., Germ., Steph., Schonh. 



— Loti, Gyll. 



— incrassaturn. Germ. 



Very rare in the south of England, but I found it in Yorkshire 

 in profusion on the black thorn {Prunus spinosa), growing on a 

 hedge-bank by the side of a ditch full of rushes in a marshy 

 situation. 



36. A. HooTceri, Kirb., Germ., Gyll., Steph., Schonh. 



I have frequently taken this insect in abundance in Yorkshire 

 by sweeping in clover-fields {Trifolium pratense), particularly in 

 a field near Low Harrowgate, in June and September; and plen- 

 tifully near Southampton in June ; one example was found at 

 Gravesend in June, and another at ShMey Common in Septem- 

 ber, by Mr. S. Stevens. 



[To be continued.] 



LI. — On the British species of Grammonema and Eunotia. 



By John Ralfs, Esq., M.R.C.S., Penzance*. 



[With a Plate.] 



Grammonema, Ag. 

 Filaments gelatinous, elongated, flexible, not fragile ; frustules 

 rectangular, plane, not striated, scarcely siUceous. 



In appearance this genus comes very near to Fragilaria, w4th 

 which it is united by most wiiters, but its habit is so very diiFer- 



* Read before the Botanical Society of Edinburgh, February Sth, 1844. 



Ann, S^ Mag, N, Hist, Volxm. 3H 



