TAYLOR : ON HELIX ARBUSTORUM. 245 



The LINGUAL RIBBON is long and narrow, the teeth being ar- 

 ranged in rows, something after the fashion of a printer's brace 

 — Y — but with the central point not so acute. 



The formula in the specimen examined by me was — 

 36—1 — 36 _ The central tooth has a base of attachment 



140 - I O) 2 20 ^^^^Yi longer than broad, with concave 

 lower margin, and has a single large median cusp, with a_ small 

 undeveloped one at either side. The lateral teeth are of similar 

 type to the central, but are deficient of the inner angle of the base 

 of attachment, the outer laterals have a side cusp, and cutting 

 point, the transition from laterals is shown by the greater propor- 

 tional development of the cutting point, which becomes bifid, and 

 lesser development of the cusp. The marginals have the reflection 

 larger than the base of attachment, the reflection is produced into 

 two lobes, the inner one bearing two cutting points, and the outer 

 a short conical one. The outermost rows are simple spikes. 



Dart-sac single, clavate, slender, livid blue in adults. Outer 

 sac, grey, semitransparent, tough; inner sheath dark brown show- 

 ing through the outer and giving it its lead-colored appearance. 

 The sac is embraced by the two stout, subulate simple arms of the 

 mucous glands. These are somewhat stiff, livid brown, andabout 

 21 mill. long. The only other British Helices resembhngit in this 

 respect are ffeh'x lapicida and H. Pisana. 



Dart. Shaft curved, slender, cylindrical, white, calcareous, 

 more or less perforated longitudinally, expanding rather abruptly 

 at about two thirds from the base into a broad, lanceolate, sharply 

 pointed head, lenticular in transverse section. Base infundibuli- 

 form not connected by a contracted neck. Length 5 mm. 



The word 'dart', giving as it does the idea of free transit 

 through the air, is I apprehend a misnomer, as appHed to this 

 organ. The manner in which it is attached to its sheath, renders 

 such an action unlikely if not impossible. I believe it to be merely 

 exserted and then plunged or pressed forwards; when it has punc- 

 tured the skin of the other snail it is frequently torn away from its 

 sheath-attachment and remains pendant by its point (Ashford). 



Otoliths rather more thah one-hundred (Moq.-Tan.). 



