Mr. A. W. Bennett on Phint-Life, d-c. 39 



Although I found one or two fragments of igneous rocks of a 

 basaltic nature, I failed to find any blocks of granite, such as 

 were found in some excavations in the glacial clay in the city of 

 York, although of course such were probably there, for the 

 exposed surface is but a very small percentage of the actual bulk 

 of these deposits. I next examined the glacial deposits near 

 Whitby. These lie also to the north chiefly, and overlie, and in 

 some instances cover, the face of the older liassic rocks between 

 Whitby and Sandsend. The clay here was very similar to that 

 of Saltburn, and probably formed one of the arms of a bifurcating 

 glacier. The lecturer then quoted several extracts from the 

 works of early geologists upon the same subject, and concluded 

 his paper with a reference of the Geology of Whitby. 



54. — Plant-Life in our Ponds and Ditches. [Abstract.] 



By Alf. W. Bennett, M.A., B.Sc, P.L.S. 



(Bead November 11th, 1885.) 



Mr. A. W. Bennett gave a description of some fresh-water 

 Algfe, illustrated especially by species met with by himself during 

 a stay last summer in Westmoreland. 



He spoke first of all of the genus Nostoc, of which several species 

 (N. comiimnis, humifiisum, &c.) are familiar terrestrial Algae, con- 

 sisting of minute interwoven strings of green cells imbedded in 

 masses of yellowish jelly. One or two aquatic species are known, 

 but none have hitherto been recorded in Britain. Mr. Bennett 

 described a new s]Decies of this set (X hyalimim), which he found 

 floating on bog-pools. It is an extremely minute nearly spherical 

 mass of colourless hyaline jelly, floating freely in the water ; in 

 the jelly is imbedded a single thread of green cells, among which 

 are here and there the larger cells known as " heterocysts." 



The principal part of the lecture was devoted to the class of 

 Conjugate, distinguished by its peculiar mode of reproduction by 

 " conjugation." The class is divided into three families, the 

 Zyrinemacea, Desmidiece, and Diatoviacem. No special reference 

 was made to the diatoms ; but the process of conjugation in the 

 filamentous Zyfinemacca; was described, as illustrated in the well- 

 known genera Zijgnema and Sjiirogyra. 



The Desmids are an extremely interesting class of fresh-water 

 organisms, to which a comparatively small amount of attention 

 has been paid in this country since the publication of Ealfs's 

 great work on the British Deswidieic in 1848. The species are 

 numerous, very abundant in fi-esh water, both stagnant and 

 running, and many of them extremely beautiful and very easy 



