HARDWICKE'S SCIENCE-GOSSIP. 



31 



hanl blocks when exposed to weather action on the 

 shore. Below this, clay occurs again, one band of 

 which is noted for the profusion of Ccrithiitm tri- 

 zonatum and Cyrena obovata, which weather out 

 very well. 



Nothing of particular note now is seen till near 

 Lynchen Chine, where a bluish clayey sand with 

 Potamomya gregaria rests on a slimy clay which con- 

 tains Cerithmm vcntricosnm and Mclania muricata, 

 and in which Mr. Keeping and myself found Ceri- 

 thitiin concaviim. This important bed is classed, as 

 the top of the Middle Headon by Messrs. Tawney 

 and Keeping. It holds up water, and makes the 

 Middle Headon beds difficult to get at all along 

 Colwell Bay. The next important bed in the Middle 

 Headon is the so-called Venus bed (so named 

 from its profusion of Cytherea (Venus) incrassata), 

 which contains a considerable number of characteristic 

 marine and brackish water-fossils, such as Fiisiis 

 labiatus, Natica labcllata, Pkurotoma macilenta, 

 Psaimnobia compressa, Aticillaria bnccinoidcs, Balanus 

 tingiiiformis, most of which can soon be collected with 

 the end of a knife and a little care from the greenish 

 clayey sand which forms this bed. It is well exposed 

 at Bramble and Colwell Chines. A curious phe- 

 nomenon occurs opposite How Ledge, for the whole 

 of the IMiddle Headon is replaced by a great oyster- 

 bed packed with Ostrea veZata, and in which may be 

 found other fossils, such as Murcx sexdentatus, 

 Melaiiopsis nsiformis, Nuada Headonensis, &c. Near, 

 or on, How Ledge too we were so lucky as to see 

 a very curious exposure of the basement bed of the 

 Middle Headon, a dark clay with an immense number 

 of specimens of Neritina coiicava, Cyrena obovata, 

 Cerithitiin pseudocinctum, Hydrobia pupa, and Natica 

 Studeri. This bed was exposed just above the How 

 Ledge limestone on the strand at How Ledge, the 

 long-prevailing east winds having swept it clear of 

 shingle and stones. The Venus bed crops out a 

 little south of Warden cliff battery. 



The most notable beds in the Lower Headon are, 

 in descending order : I. The bed of limestone which 

 rises from How Ledge and forms a well-marked 

 terrace in the northern part of Totland Bay ; 2. the 

 Warden Ledge sands, rising at Warden Ledge and 

 forming a lower terrace : their base is a band of 

 sand with Potamomya ; 3. bands of clay and limestone 

 (with Chara and Limncea), the lowest beds exposed 

 by the anticlinal of this bay. Specimens of Limnssa 

 and Planorbis may be collected, by using strong gum 

 water, from the tumbled blocks of the hmestone (i) at 

 Warden Point. The exposures in the middle part 

 of Totland Bay are grassed and plastered over, but 

 here and there the limestones (3) may be observed, 

 and the Warden Cliff sands (2) crop out in a few 

 places, and are distinctly seen to bend over in an 

 anticlinal near Western Chine. 



(To be continued.) 



POND-COLLECTING IN MID-WINTER. 



THERE is an idea abroad among naturalists that 

 in winter time all ponds are quite barren of 

 life. Conchologists, I have observed, are particularly 

 infected with this notion, but my own experience has 

 uniformly contradicted it, although my collecting 

 has been carried on in a neighbourhood which has a 

 very low winter temperature. 



On the 2nd of January I fished some old brick 

 ponds near York. The net brought up crowds of 

 Valvata cristata, the specimens being fine an d large. 

 It was accompanied by Platwrbis lineatiis, and the 

 ubiquitous P. complanatiis and L. peregra. From 

 some reason, which I cannot explain, I have taken in 

 winter larger specimens of certain shells than I could 

 ever obtain in the same locality in summer. The 

 three species I refer to are L. palustris, L. peregra, 

 and Physa hypnortim. 



The beetles were not numerous in this pond — 

 Hydroporiis palustris, Noterus crassicornis and a few 

 of the Philhydrida were all I saw. However, on 

 taking a haul in an adjacent puddle I found two 

 very good things — Hydroporiis rufifrons and Agabus 

 idiginosus. These insects were in full vivacity— un- 

 like the other species which appeared numb. Among 

 the specimens of A. uliginosus were examples of the 

 dull-backed female. It is a curious fact that two 

 forms of the female are found in England, though 

 only one is known on the continent. A striking 

 feature in a pond-haul at this season is the number 

 of coleopterous larvae which appear. The transfor- 

 mations of these insects have only been imperfectly 

 studied, and it would no doubt be very interesting 

 and profitable to obtain a number of these larvse in 

 winter and rear them with careful observation. 



In the same pond where these beetles occurred, 

 were great numbers of Planorbis spirorbis, remark- 

 able from the fact that a considerable portion of the 

 specimens were more or less irregular in form— not 

 scalariferous, but crumpled or waved. 



Such irregularities are not easy to explain, for (as 

 in the present case) they often occur where the water 

 is perfectly clean and quite stagnant. In a neighbour- 

 ing pond, where Ancylus lacustris, Planorbis nitidus, 

 Sphccrium laciistre and other species are perfectly 

 well grown, nearly all the specimens of L. peregra 

 that paragon of hardiness— are dwarfed and strongly 

 decollated. I shall be glad if these remarks induce 

 any of your readers to keep their nets in order in 

 winter as well as summer. 



Rev. W. C. Hey, M.A. 

 The Residence, York. 



PoLARiscoi'E Objects .—Can your readers give me 



a full list of polariscope objects, with full instructions 

 how to mount some, including crystals, salts, &c. ?— 

 John Alex. Ollard. 



