April.! Excursion to Burnley Oiiarries. 177 



1917 J 



the innumerable small columns radiating from a centre like 

 the ribs of an extended fan. After spending some little time 

 in examining these interesting geological features, attention 

 was turned to the business of pond-searching, with good 

 results, as a very small pool, only a few feet across, yielded two 

 very uncommon algae, both belonging to the family Ulvaceas. 

 One was of a filamentous type, and covered practically the 

 whole of the bottom of the pool as well as some of the surface 

 of the water. On examination it proved to be an Enteromorpha, 

 possibly E. intestinalis. In this alga the thallus is tubular, and is 

 composed of a single stratum of cells, the tubes being extremely 

 attenuated in the specimens collected. The second alga was 

 a Monostroma, probably M. menihranacea. West. Some years 

 ago, on the occasion of a Club excursion, a remarkable alga 

 was discovered in one of these quarry-holes. It resembled 

 sheets of green tissue paper or lettuce leaves floating in the 

 water. Specimens were submitted to Professor West, of Liver- 

 pool, by Mr. A. D. Hardy, F.L.S., with the result that it was 

 pronounced new to science, and received the name Monostroma 

 expansa. As far as we know, this plant has not been recorded 

 from any other locality. The alga taken on the recent visit 

 differs from M. expansa in some respects, the cells in the 

 thallus being larger, and the thallus itself in every case long, 

 narrow, and ribbon-like instead of being broadly expanded. 

 The thallus of M. memhranacea, as described by West, how- 

 ever, is very much shorter relatively than that of the one just 

 collected ; the difference, however, may be the result of a more 

 robust growth in the case of the Victorian type. After 

 spending half an hour or so hereabouts, a move was made to 

 the ponds at the western end of the excavations, where the 

 best results are generally obtained. On arriving there a search 

 was first made for the fresh-water crab, Hymenosonia lacustris, 

 a few specimens being obtained. A fine Dragon-fly nymph was 

 next taken, which gave Mr. J. Searle the opportunity of 

 demonstrating the existence of the extraordinary organ known 

 as the mask, a part of this insect's anatomy to which reference 

 was made in his recent paper on "The Pond and its 

 Inhabitants." Another very interesting capture was a larva 

 of an Ephemera, or May-fly. This immature insect is fur- 

 nished with three feather-like caudal appendages and a row 

 of external breathing organs or gills on each side. Although 

 the mature Ephemera has a life of a few hours only, the larva 

 has an existence extending over two or three years. Caddis-fly 

 larvae were also in evidence. These queer creatures construct 

 tube-like residences for themselves of various materials, which 

 they drag about with them as they crawl or swim about. The 

 fresh-water shrimp, Xiphocaris, sp., was secured in fair 



