2 ON BRITISH SPECIES OF ISOÉTES. 
sistent hardened. leaf-bases, which terminate in three. curious spines, 
which he calls Z. Durigi, and the T. lacustris, which totally wants those 
hard parts, nevertheless is manifestly unwilling to allow of the existence 
of any others. I can only suppose that he has never examined with 
the microscope the structure of the macrospores of the plants, for, had 
he done so, it is scarcely possible to believe that he could arrive at such 
a conclusion. 
But it is not proposed to enter here into a discussion of the distine- 
tive characters of the species mentioned above, of which the first six - 
belong to the Z. lacustris of. Hooker, and the seventh and eighth to his 
T. Duriai, but to give a popular account of the proceedings of myself 
and others in the discovery of J. echinospora in England and Scotland, 
and J. Hysíriz in Guernsey. To begin with J. Hysíriz, Dur., which, 
having as yet been found only in Guernsey, has no true claim to be in- 
cluded in the British flora. My first information of its discovery was 
contained. in a letter from a very intelligent and obliging gardener in 
Guernsey, Mr. G. Wolsey, dated. 15th October, 1860.. It contained a 
bit of the Zsoctes, asking its name, and mentioning that it was found on 
L’Ancresse Common, in Guernsey, in June. of that year, ..Atasubse- 
quent time I obtained several more good specimens of the plant from 
him, and was enabled, by careful examination, and the comparison of 
of them with the plate (36) of T. Hystriz and I. Duriei contained in the — 
‘Expédition scientifique de l'Algérie; and. the descriptions given by — 
Cosson in * Notes sur quelques Plantes nouvelles ou critiques’ (p. 70), 
and the * Comptes-rendus de l’Académie des Sciences,' xviii. 1167, to 
ascertain with certainty that Wolsey's plant is the 7. Hystriz.. Before 
such examination, Dr. Joseph Hooker was of opinion that it was Z. 
Duriei ; but it must be added that he had no macrospores to examine, 
for the first specimen sent to me, and shown to him, retained only the — 
microspores, Our specimens are very similar to some kindly sent to 
me by Gay, as gathered by Durien “ in graminosis arenosis siccis circa 
Vasconiz maritime lacum. Cazau,” in July, 1860. He marks it as 
“ forma phyllopodiis abbreviatis," in which respect, the Guernsey and 
Cazau specimens differ remarkably from those from Algeria, —remark- 
appearance, not in reality ; for. the structure is 
the same, but the persistent phyllopodes are fewer in number and 
shorter. Indeed, even the Algerine specimens now before me are not 
nearly so spinous as that which was selected for delineation in the 
