HARDWICKE'S SCIENCE-GOSSIP. 



THE VARIATION AND ABNORMAL DE- 

 VELOPMENT OF THE MOLLUSCA. 



By T. D. A. Cockerell. 



Part V. 



WHEN, in 1885, I commenced a series of papers 

 in the columns of Science-Gossip under 

 the above heading, it was my intention to consider in 

 due sequence the phases of variation exhibited by the 

 land and fresh-water mollusca of south-eastern 

 England, with occasional references to those of other 

 countries when necessary for the elucidation of the 

 matter on hand. These papers were discontinued 

 when I left England, but, with the Editor's permission, 

 I will now proceed to treat of the remaining species. 



rubella oo 311 o, Pontefract (G. Roberts) ; var. libcllula 

 °°3i5> Valentia, Ireland (Rev. A. H. Delap) ; vars. 

 rubella (: : : : :), rubella 1 (: : : :), and rubella (::):: :, 

 Dublin (J. R. Redding). With regard to these last 

 three I have always taken the colon, as used in band- 

 formula by French authors, to indicate a band inter- 

 rupted at intervals, and it is so used here. The first 

 variety (:::::) has five coalesced interrupted bands, 

 the result being transverse markings, which are un- 

 dulating or zigzag. This is extremely interesting as 

 pointing to the way in which such markings were 

 developed in species which now normally possess 

 them. I believe this particular variety of H. nemoralis 

 is var. uttdulata, Gentiluomo (1868), and Mr. "Wilcock 

 once sent me a drawing of it marked var. transversa, 

 Wilcock MS. 



Fig. 1. — Helix hortensis, var. mi?ior. 

 Bickley, Kent. 



Fig. 2. — Helix bourcieri. 

 Quito. 



Fig. 3. — Helix moricandi. 

 Philippines. 



g. 4. — Helix carpenteriana. 

 Florida. (Enlarged.) 



Fig, 



5. — Helix erronea. 

 South India. 



Fig. 6, 



-Helix conoidea. 

 Mogador. 



Fig. 7. — Clausilia rugosa, var. 

 gracilior. Battle, Sussex. 



Fig. 8. — Mouth of C. biplicaia, "monst. 

 tridentaiian." Near Hammersmith. 



Fig. 9. — Pisidium atnnicum, from Cray- 

 ford fossil-pit. Showing constriction of 

 valve, which is common in the Crayford 

 Pisidia and Sphseria. 



Part IV. treated of that polymorphic species, Helix 

 nemoralis ; and before leaving this subject, it may 

 be well to record a few hitherto unpublished band- 

 varieties of this and H. hortensis that have come 

 under my notice. 



H. nemoralis: var. rubella o„34 5 , Pontefract (G. 

 Roberts) ; var. libellula 0O345, Weston-super-Mare 

 (Hele, in coll. Ponsonby) ; var. libellula 003(45), 

 Derbyshire (Milnes) ; var. rubella 12 3 45 , near Chisle- 

 hurst (S. C. Cockerell); var. rubella ooo 4 5, Truro 

 (J. H. James) ; var. rubella I2 3 45, Truro (James) ; 

 var. libellula oo( 34 5), Truro (James) ; var. libellula 

 ooo 4 5, near Bardowie Loch, near Glasgow (Alex. 

 Shaw) ; var. rubella 000(44)0, band 4 appearing 

 as a double band which joins near the aperture, 

 Martlock, Somerset (Rev. H. Friend) ; var. libellula 

 ©23(45)1 Brackley, N. Hants (Rev. H. Friend) ; var. 



The list of pale-lipped forms might be added to 

 considerably, if the various combinations of banding 

 and colour were taken into account. 



The vars. roseozonata-albolabiata and eilrinozouata- 

 albolabiata have both been sent me from Yorkshire by 

 Mr. G. Roberts. The description of the latter should, 

 of course, read "bands pale yellow," not brown, 

 as given in Part IV. Var. roseozonata-roseolabiata 

 has been sent from Truro by Mr. James. I am by 

 no means clear, however, that priority does not 

 demand the substitution oihybrida, Poiret, and hybrida, 

 Jeffreys, for the varietal names roseolabiata of H. 

 nemoralis and II. hortensis respectively. The thin 

 var. tenuis, Ckll. MS., Marquand, is from Truro and 

 Falmouth, and probably is caused by want of lime. 

 Professor F. Jeffrey Bell (Comp. Anat. and Phys. 

 1885, p. 305), states that no shelled forms occur at the 



