— 158 — 



Zur Terminologie der Molluslieu-Skulptar. 



Von 

 W. H. Dali.*) 



A term for indicating the direction of the sculpture 

 which crosses the whorls in general harmony with the 

 axis of a spiral shell, in contrast with that wich follow? 

 the coil, has long been needed. The latter is generally 

 and appropriately termed ..spiraV" . The former has been 

 called „transverse\ meaning transverse to the line of coil, 

 but not transverse to the axis; and longitudinal, a term 

 which also has been used as synonymous with spiral. 

 Both of these terms are ambiguous. „Verticar' has some. 

 times been used, but when the sculpture in question is 

 sinuous or oblique, it sounds disagreeably like a contra- 

 diction in terms. Some years ago J proposed to use the 

 term ^,axial'' for this sculpture, though in many cases it 

 does not mathematically coincide with the axis of revolution; 

 yet it seemed appropriate brief and comprehensible. Jf, 

 howewer, anything less liable to miscomprehension and in 

 general more suitable, can be suggested, J shall be glad 

 to adopt it. It should be remembered, in considering the 

 subject, that the axis is not always vertical, and that ver- 

 tical is an absolute term, vertical sculpture cannot logically 

 be oblique, sinuous or arcuate, while an axis may be either, 

 as, for instance in Streptaxis or some Eulimas. — 



For the direction of axial ribbing or other sculpture, 

 which is not strictly parallel to a vertical axis, concise 

 terms are also needed to indicate whether the ribs slant 

 forward from the summit of the whorles at the preceding 

 suture, which migth be called ,,protractive'\ or back ward, 



*) Wir bringen diese in einer Anmerkung in der Bearbeitung 

 der Albatross-Bucciniden (Smilhson Miscell. Coli. No. 1727, Quarterly 

 Jssue No. 50 part. 2) hier zum Abdruck, da diese Frage immer nach 

 nicht gekUrt ist. :Lf'Mt,lioO 



