8 4 



SCIENCE-GOSSIP. 



rather large cilia ; at the posterior end is the anus. 

 A spherical nucleus is present in the middle of the 

 body, and one contractile vacuole posterior to it. 

 Zoochlorellen may sometimes be observed. 



This species is exceedingly common and widely 

 distributed; it occurs in stagnant water; the 



Fig. 23. — Coleps liirtus. ( x 335.) 



body length is about 70 microns. The process of 

 transverse fission is as follows : The cuticle 

 becomes separated in the middle, and the body 

 becomes much elongated, the central portion being 

 without corrugations. The centre then becomes 

 constricted and finally cut right through, and two 

 animals are formed, one with corrugated cuticle at 

 its anterior end, the other thus protected at its 

 posterior end. These two animals then proceed to 

 grow gradually into the normal form. 

 (To be continued.) 



HELIX NEMORALIS IN IRELAND. 



By John T. Carrington. 



T AM again indebted to Mr. R. Welch, of Belfast, 

 for a consignment of shells of Tachea nemoralis 

 from Co. Down. The former batch was described 

 in Science-Gossip in May last (vide vol. iv. N.S. 

 p. 352). These last were kindly gathered by Mrs. 

 Robert Russell, of Belfast, on sand dunes at 

 Killard Point, near Portaferry. Mrs. Russell sent to 

 Mr. Welch 829 specimens, collected "just as they 

 came, without selection," a large proportion being 

 immature. The mature examples were much eroded 

 by sand blowing and weather wear. Mr. Welch 

 retained forty-eight examples for his collection 

 and the Irish collection in the Dublin Museum 

 These are included in the following analysis of 

 variation occurring in the batch. He chose the 

 forty-eight on account of small size or inclination 

 to have high spiral formation. 



The general tendency in size of the Killard Point 

 T. nemoralis is to run small, though there are 

 individuals up to the average. Mr. Welch retained 

 some small examples under 18 mm. broad. He 

 suggests it is the result of the past cold spring. 



This may account for the large number of immatur 

 specimens, but not for the puny adults, which, 

 being much eroded by sand blowing, evidently 

 belong to last year. Sandhill specimens are often 

 smaller than those on better soil. There is some 

 tendency to have high spires, one example being 

 quite the form conica. 



The colour varieties are three in number, viz., 

 545 yellow (var. libellula), 238 pink (var. rubella), 45 

 orange (var. aurantia) = 828 specimens. 



The band formulae are as follows : 



No bands .. 00000 .. 1 specimen. 

 Split bands, 00,5340 and 123445, 2 specimens. 



1 band .. 00300 .. 213 ,, 



2 bands . . 10300 . . 4 ,, 

 2 ,, . . 02300 . . 2 ,, 



2 ,, .. 00305 .. 6 ,, 



3 ,, .. 12300 ..1 

 3 ,, .. 02340 .. 2 

 3 ,, .. 02305 ..1 

 3 .. •• 10305 7 



3 .. •• oo345 •• T 5 



4 » •• I20 45 3 

 4 ,, .. 10345 ..4 



4 ,, .. 02345 ..1 



5 .. •- "345 •• 319 



2 ,, in 1 . . 0(23)00 . . 1 ,, 



3 ,, in 2 . . 1(23)00 . . 1 ,, 

 3 „ in 2 .. 0(23)40 ..1 



3 ,, in 2 .. 003(45) ..2 



5 ,, in 1 .. (12345) ..2 



5 ,, in 2 .. (123M45) •• c 3 



5 ,> in 3 •• (12)3(45) •• 3 



5 ,, in 3 .. (123)45 •• 85 



5 .. in 4 •• J ( 2 3)45 •• 21 

 5 „ in 4 .. (12)345 -.69 



In the colour varieties, yellow largely predomin- 

 ates over the others. Some of the pink specimens 

 are rather dark or richly coloured, but many others 

 showed a tendency to the orange tint. This also 

 appeared slightly in a few of the yellow examples. 

 I think when these animals are bred by artificial 

 selection, it will probably be found that the var. 

 aurantia may be often obtained by crossing the 

 pink and yellow forms. 



With regard to the band variation, the following 

 points were noted. 



The occurrence of only one bandless (00000, 

 lihetlula) among 828 specimens gathered " as they 

 came," is remarkable, and tends to show that the 

 band formulae are hereditary in localities. The 

 absence of bands is the more notable when we find 

 about a fourth of the whole had only one banded 

 00300. 



The proportion of colour in the one-banded 

 form was about equal in average to that of the 

 numbers respectively of the three colour forms 

 represented. Some of these single bands were 



