126 JOURNAL or CONCIIOI.OGY, VOT,. I4, NO. 4, OCTOBER, I913. 



either in shell or flesh, the latter being white, fat, full, and succulent. 

 Its only natural enemy appears to be the crab, which finds it an easy 

 prey. 



It has been found that in the hardest frost the mussels become 

 frozen but do not die, as they thaAV and melt on a rising temperature, 

 and seem none the worse for it. Not so the oyster, which is killed 

 off by frost. It also bears greater heat and exposure than the 

 oyster. Mussels, in fact, appear to be particularly tenacious of life, 

 as a cart-load of them, which had been shot into a hole and covered 

 with two feet of clay because they were all thought to be dead, were 

 found some weeks later alive and thriving, and working tlieir way out 

 of the clay mass in which they were embedded. 



var. incurvata Penn. — This variety is not always "stunted and 

 bent," and " filling crevices of rocks ;" on some coasts it lives 

 attached by a byssus only ; in this state it is small and narrow, 

 beautifully rayed, and curved like the blade of a scythe ; hence the 

 name. 



var. pellucida Penn. — Among some beautiful specimens ot this 

 variety which were taken from the bottom of a barge at New Ferry 

 by Mr. A. Leicester, a portion possess some peculiar features. 

 Instead of bemg "less gibbous" than the type, they are much more 

 so, the umbonal area especially being swollen to the same extent as 

 in M. modiolus^ and, like that species, the anterior end of the shell is 

 broadly rounded and swollen, instead of forming a point. In outward 

 form they would answer for either species. 



var. pallida Marsh, must be substituted for vax.flavus Poli, to 

 which I attributed it in error. Poli's shell is brownish-yellow, and 

 hardly a variety, though it is found occasionally on our coasts. Var. 

 pallida is straw-colour or colourless. Another form sometimes found 

 on our coasts is smaller, narrower, and proportionately longer ; this 

 is var. elougata S. Wood, from the Crag. I have it from Southampton 

 Water. 



M. modiolus var. ovata Jeff. — Tenby (Span) ! 



var. cylindrica Marsh. — This is well figured as an elongated 

 variety in Crag MoUusca, vol. ii., tab. viii., figs, ic, d. 



M. barbatus L. — The Bute record of Mr. Wotton is an error, 

 his shell being M. ??wdiolus. Other Clyde records given in Brit. 

 Assoc. Handbook (1901) are most probably equally erroneous, and 

 the determination not only of this species, but of many others in that 

 list, should not be accepted without confirmation. 



Adula (Myrina) simpsoni Marsh. — Described and figured in 

 Journ. Malac, 1900, vol. vii., p. 167 (woodcuts); and vol. viii., p. 19. 



Modiolaria marmorata Forb.— Frith of Forth, living at low 

 water (Jeffreys). 



