HARD WICKE'S SCIENCE- G OS SI P. 



67 



ZOOLOGY. 



A New Variety of Rotifer. — A new and well- 

 marked variety of Philodina citrina has recently 

 occurred in a stream near Cheadle, Staffordshire. Its 

 form is strikingly different from that under which the 

 species has been known, as it is very slender, with 

 no clear distinction between the body and the foot. 

 The colour is generally brown rather than yellow, 

 and is not confined to the central parts. Mr. Gosse, 

 who has seen many specimens from the stream 

 already mentioned, thought at first that this form 

 was a distinct and undescribed species, but afterwards 

 concluded that it was a variety of Philodina citriua, 

 a species which he had always hitherto considered 

 rare. This variety has the social habits described 

 by Mr. Gosse in "The Rotifera," by Hudson and 

 Gosse, vol. i. p. 101. It is generally rough, with 

 extraneous matter adhering to the surface. The eyes 

 are very minute. — J. IV. Blagg, GrcoiliiU, Clicadlc, 

 Staffordshire. 



Breconshire Mollusca.— The following list of 

 species, sent to me by Mr. F. W. Watton, from 

 Langorse Lake, Brecon, may be of interest as a 

 contribution to the molluscan fauna of the country : — 

 Valvata cristata, V. piscinalis, Bythiuia tcntaculata, 

 Planorbis umbilicatns (— complanatus of Jeffreys), 

 P. nautikus, type, Physa hypnorum, limiKca peregra, 

 L. pa/ustris, L. truncatula, Pisidium pusilluin, type 

 and var. circularis (3 mill. diam. greyish, rather 

 shiny, almost circular in outline, subtruncate an- 

 teriorly, beaks almost central), and Anodonta anatina. 

 Ancylus fluviatilis was sent from the river Usk, and 

 Planorbis carinatns from the Brecon canal. — T.D. A. 

 Cockcrcll. 



Variation in Helices. — A remarkable case has 

 recently come under my notice which may tend to 

 throw some light on the cause and nature of colour- 

 variation in the shells of mollusca. Specimens of 

 Helix aspcrsa, II. nemoralis, and //. hortensis, col- 

 lected on the same bank at Torquay by Mr. F. W. 

 Wotton, and forwarded to me for examination, 

 belonged to undescribed varieties of their respective 

 species, all three exactly analogous, and caused no 

 doubt by the same conditions. The peculiarity con- 

 sisted in the straw-yellow tinge of the ground colour, 

 and the red-brown colour of the banding or markings, 

 as follows : H. aspcrsa v. lutescens, ground colour 

 yellow, more or less vivid, bands pale red-brown, 

 lip white ; H. nemoralis v. rufozonata, with red- 

 brown bands, and having the pale-lipped character 

 of var. hybrida > II. hortensis v. rufqzonata, with red- 

 brown bands. With the // aspcrsa from Torquay 

 one specimen also of var. unicolor was sent, together 

 with //. rnpcstris, H. concinna, II. caperata, and 

 szx.fuha, and other species. A somewhat similar 

 instance occurred in specimens of II. nemoralis v. 

 lutcolabiata and II. hortensis v. Intcolabiata, which 



were found by Mr. T. H. James at Truro ; in both 

 of these varieties the lip has a decided yellow tinge, 

 in some specimens as vivid as the pink in roseolabiata, 

 the variety of nemoralis being of course pale-lipped. 

 Altogether there seems to be no longer any doubt 

 that certain variations occur in all allied species 

 under certain conditions, and I think that it is in the 

 careful investigation of these conditions that our hope 

 lies of discovering the true nature of many forms of 

 variation which are at present quite unexplained. 

 Nor is it only in colour-varieties that this holds true. 

 Mr. G. Roberts has found trochiform II. ?iemo?-alis 

 and II. arbustoritm living together near Wressle, in 

 Yorkshire; Miss Hele has taken sinistral //. hortensis 

 and H. aspcrsa in the same neighbourhood, near 

 Bristol, and the Rev. W. C. Hey found reversed 

 H. virgata at Coatham, within a few yards of the 

 spot where he had previously taken reversed //. 

 aspcrsa* Such instances as these are frequently 

 brought to light, and seem to me to signify much to 

 those interested in the solution of these problems. — 

 T. D. A. Cockerel!, Bedford Park. 



Turbellaria Swallowino Air. — Last summer 

 I was examining some pond water on a slide, when I 

 came across one of the Turbellaria of the group 

 Rhabdoccela. Beneath the cover-glass were some 

 bubbles of air ; I saw the worm deliberately swallow 

 one of these, two or three minutes after the glass was 

 put on. The bubble remained below the mouth at 

 the top of the straight alimentary canal ; it was very 

 large compared with the size of the animal, and 

 extended nearly from side to side. The bubble 

 gradually decreased in size, and in five minutes had 

 disappeared altogether. The air was not ejected 

 from the mouth, but simply absorbed into the body 

 of the worm. As I have not seen this recorded any- 

 where, it seems to be worth mentioning. Where did 

 the air go, and what became of it ultimately ? — J. C. 

 Grccnfell, Clifton. 



The Parietal Eye of the Lizard. — On the 

 bottom of p. 161 in your Gossip of last year you 

 make mention of Mr. Baldwin Spenser's communi- 

 cation to the pages of " Nature " on the parietal eye of 

 Ilatteria punctata. There are to me interesting 

 features connected with this which you omit. It is 

 known that this parietal eye leads back by an optic 

 nerve, which is connected with the pituitary body. 

 Descartes thought this last-named structure in us was 

 the seat of the soul. Hitherto physiologists have 

 given the function of this organ up as almost 

 unknowable. I believe Morse, of America, has 

 described tertiary lizards in which the parietal 

 foramen is a complete orbit, with well-defined pro- 

 cesses and roughnesses of the surrounding bone for the 

 attachment of the orbital muscles. Here, then, is a 

 necessary solution of our pituitary body : it is a 



* " Naturalist," 1887, p. 20. 



