238 PROCEEDINGS OF SOCIETIES. 



in the present form be taken for some possibly undescribed alga, 

 whilst the refringent " heads," in the active state, though in as- 

 pect and nature not seemingly materially difierent, except perhaps 

 in size, from the similar bodies forming the joints or links in a 

 Vibrio, &c., still, from their occupying but one extremity, would 

 more forcibly call to mipd the " spores " of certain veritable Nos- 

 tochacean forms ; they are sometimes detached and met with 

 separately. This when in the active or moving state is a very 

 agile form, incessantly darting backwards and forwards, and 

 " poking " its way into and again out from the masses of " dirt " 

 and heterogeneous objects around. 



18fk Novemler, 1875. 



Notice of some Desmidian forms allied to Closterium ohtusum, 

 Breb. — Mr. Archer showed specimens of two new doubtlessly Des- 

 midian forms closely allied to, but distinct from, that referred to 

 Closterium under the name of Cl.obtusum by de Brebisson. One was 

 long, very slender, slightly curved, and ends truncate, close to which 

 a colourless space, without granules, beyond the medium longitu- 

 dinal string of green contents. The other was considerably stouter, 

 margin subparallel for a considerable distance, towards the ends 

 somewhat suddenly attenuated ; apices bluntly rounded, close to 

 which a colourless space beyond the median longitudinal string of 

 green contents, containing a single fixed and still granule. In both 

 forms the nucleus was excentric, and placed in a lateral depression 

 of the endochrome-mass. It will be seen that these hardly accord 

 with the characters of Closterium. Mr. Archer thought it 

 possible that, with some two or three others kindred thereto, they 

 might take a place as a distinct genus close to Closterium and 

 Penium, as well as near Spirotsenia and Cylindrocystis. Before 

 arriving at a conclusion some of the other forms in view would 

 have to be refound and submitted to a further study. 



Aulacodiscus Johnsonii, exhibited. — Kev. E. O'Meara showed a 

 fine mounting by the Club's Corresponding Member, Mr. Kitton, 

 of Norwich, oi Aulacodiscus Johnsonii ; in one instance the num- 

 ber of nodules on one valve was greater than on the other. 



Structure of Petioles in genus Nymphcea. — Mr. Mackintosh ex- 

 hibited transverse sections of the petioles of Nympheea odorata and 

 N. ccerulea, along with N. alba, all belonging to the series with 

 stellate cells in their air-passages, and which might therefore be 

 termed " asteridiophorous." So far as he could make out, the only 

 difference discernible in the petioles was in the number of secondary 

 air-passages, which were generally two in A'^. odorata, from six to 

 eight in N. ccsrulea, and from nine to twelve and even more in N. 

 alba. The number of primary air-passages was four instead of 

 ten, as in the " anasteridiophorous " series, examples of which 

 were exhibited at last meeting of the Club. 



Tetraspores in Stennogramme interrupta. — Dr. E. Perceval 

 "Wright showed examples with tetraspores of Stennogramme inter- 

 rupta, and referred to a notice in ' Grevillea ' by E. M. Holmes, in 



