341 

 ON THE FORMS OF LACUNA PUTEOLUS (TURTON). 



By L. St. G. BYNE, M.Sc. 



(Read before the Society, May 5th, 1900). 



During the ten years that my father, the late Mr. Henry Byne, and 

 myself worked at the marine mollusca of the Bay of Teignmouth, 

 South Devon, we had excellent opportunities of studying this variable 

 species in all its forms. We examined many thousands of specimens. 

 The species occurred in great profusion amongst seaweeds on rocks 

 at low water throughout the bay ; the rare variety expansa being 

 fairly abundant. I propose in these notes to offer some observations 

 upon the forms of this species that I have met with at Teignmouth 

 and neighbourhood, also describing new ones. 



Forms. 

 I.— Typical. 



(a). Banded. This is the prevailing modification. 



(b). Light-horn coloured. This has also occurred as a thin trans- 

 parent form with slight purple bands, and also stained with 

 carmine. This latter may be due to some secretion of the 

 animal. Some examples are greenish-brown in hue. 



(c). Whorls coloured a purplish-brown with a yellow band near the 

 apex. This variety is quite constant, and I have about fifty 

 examples. There are those who would give this a varietal name, 

 but I do not propose to do so. I have been and am still greatly 

 against burdening our list with slight varieties in colour or form. 



(d). Horn coloured with a deep purplish band around the base of 

 the body-whorl. Two specimens only among thousands of 

 ordinary form. 



(<?). Horn coloured with a thin red line or band around the body- 

 whorl. A few only. 

 I am glad to note that Mr. Marshall has withdrawn his variety 

 plicata from the list. I quite concur in his opinion that it is not a 

 valid variety, the lines being worn by attrition. 



II. — Var. expansa Jeffreys occurred mixed with the type. In one 

 instance, however, it was accompanied by large L. divaricata. I have 

 noticed several modifications. 

 (a). Light-horn coloured. 

 {!>). Banded. 



(c). Plum coloured. I am indebted to the late Mr. Burkill for ex- 

 amples of this and the next form from Penzance. 

 (d). Milk-white. Penzance. 



