HA RD WICKE'S SCIENCE- G OS SIP. 



12 



appliances that in the course of actual work have 

 proved useful and readily obtainable. 



Out here in India, scientific appliances can be 

 purchased only in the presidency towns ; and even 

 in these the stock is of a most meagre and limited 

 description. Hence, as it takes between two and 

 three months to obtain anything from home, one's 

 invention is very often stimulated by dire necessity. 

 Rude, however, as some of the methods and appli- 

 ances may appear, they have at least the merit of 

 being inexpensive, and readily obtainable anywhere. 



Did space permit, I should have much liked to 

 have concluded with a few sketches of some of the 

 queer monstrosities that get entangled in my toils, 

 but I fear I must have already unduly tried the 

 patience of my readers, and occupied far too many 

 lines of their very useful " Gossip " journal. I hope, 

 however, "if permission be accorded," as polite 

 Orientals always say in making any proposition, to 

 do this at some future time. 1 



My main desire has been to show how easily 

 surface-net work may be prosecuted, and how small 

 is the "plant" required for the purpose; and thus 

 to open up this most fruitful field of scientific enter- 

 tainment to the large numbers of microscopists who 

 annually visit the seaside, or make voyages of business 

 or pleasure. Indeed I can imagine no more pleasant 

 way of whiling away the monotony of a long sea 

 voyage than this. As yet, what experiments I have 

 made at devising a collecting apparatus for use at 

 high speed have not proved particularly successful ; 

 but sufficient material may be generally collected 

 during the halts necessary for coaling, re-packing 

 cylinders, etc., to fully occupy one's spare time in 

 the interval. 



Marine Survey Office, Poona. 



THE VARIATION AND ABNORMAL 

 DEVELOPMENT OF THE MOLLUSCA. 



Part III. 



Terrestrial Gasteropoda {continued). 



[Continued from p. 98.] 



IN Limncea and Helix scalariform specimens are 

 abnormal ; but in Scalaria hyalina and other 

 species, they are normal. According to the " Zoologi- 

 cal Record" for 1880, Helix rupestris, a species not 

 normally scalariform, is represented in the Isle of 

 Syra by very numerous scalariform individuals and 

 very few typical ones. 



Taking cases of sinistrorsion, we find that : 



(1.) Of all the genera of Mollusca a very few are 



sinistral ; e.g. Physa ; 

 (2.) of all the species of Helix, a normally 

 dextral genus of Mollusca, a very few are 

 sinistral ; e.g. H. Lvvipes ; 



(3.) of all the specimens of Helix hortensis, a 



normally dextral Helix, a very few are 



sinistral ; e.g. those found by Miss Hele 



near Bristol ; anil then again, according 



to Hartman, in the genus Partula, we 



find that in 



(1.; P. affinis, one in several hundred is sinistral ; 



(2. (in P. vexillum, one in fifty is sinistral ; 



(3.) in P. otahcitana, the majority are sinistral ; 



and 

 (4.) in P. spadicca, all are sinistral. 

 Helix nemoralis. — This most interesting species 

 may be divided into groups according to the ground 

 colour. 



(1.) rubella. Shell pink or rose colour. This may 

 again be divided into sub-varieties, according to the 

 band-formula. My notes on the subject of band- 

 formulae are very incomplete, I fear ; but I have the 

 following forms of rubella on record for the district : — 

 rubella 00000. Minster (S.C.C.), Chislehurst, 

 on fronds of Pteris, Farn- 

 borough. Not so common as 

 might be expected. 

 ,, oo^oo. (Numbers below the line are 



meant to indicate bands de- 

 veloped very little, sometimes 

 being confined to a mere trace 

 near the lip of the shell.) 

 Dartford, amongst ivy. 

 ,, 00300. Ealing, Chislehurst, Minster, 



Dartford, &c. There is 

 usually a light-coloured por- 

 tion bordering the lower edge 

 of the band, so that there is 

 an appearance of a double 

 band, the upper and larger 

 portion being dark, and the 

 lower portion light. 

 ,, 003,,0. One at Eltham. 



,, 0030^. Dartford, amongst ivy. 



,, oo, 40 and o 2345 . Dartford, with the last. 

 ,, °-345- Chislehurst, one specimen had 



the bands interrupted, but 

 otherwise well marked ; an- 

 other had continuous bands. 

 ,, 1-345- Dartford. ^345. Ealing and 



Dartford. 

 „ 12345. Ealing, Kenley, Dartford, Chisle- 



hurst, Eltham, &c. 

 ,, 120(45). O ne at Beckenham, but not 



found elsewhere in district. 



,, i(23)(45). Dartford (12345), Bickley ; other 



gradations occur. 



A monstrosity, caused by repair of fracture, found 



on Chislehurst Common, has a deep and rather wide 



umbilicus ; it belongs to rubella 00000. A specimen 



of rubella 00300 from Minster has also a thin white 



line or band, nearly in the position of band No. 10 of 



a normal specimen ; whether it is analogous to the 



G 2 



