TURTONIA. 97 



TURTONIA, Hanley. 

 T. MINUTA, O. Fabricius. 



T. minuta, Brit. Moll. ii. p. 81, pi. 18. f. 7 & 7 a ; (animal) pi. O. f. 1. 

 Mya purpurea, Montagu et Auctorum. 



I have never seen this animal, and can only record the 

 slight notes of authors, that the foot is very large, strong, 

 geniculated, and issues from the shorter end of the shell ; the 

 mantle is largely open anteriorly, and a slender somewhat 

 produced siphonal tube proceeds from the longer side. The 

 shell, except in contour, in many respects agrees with the 

 Lutirue. The ligament is external, and there are in perfect 

 specimens two cardinal teeth ? in each valve, one or both is 

 often bifid ; the teeth vary much from being deeply cloven ; 

 and thus in some examples the appearance of two, three, or 

 four is presented, and in old shells they are otherwise con- 

 fused and indistinct. The pallial impression is entire; the 

 anterior adductor cicatrix, as in many of the L/uciruR, is rather 

 more extended and at a lower level, but not much more, than 

 the posterior one. Under the microscope we discover traces 

 of the vertical lines so conspicuous in the margin of Lucina 

 borealis ; and we may also state, it is thickened, dull, and 

 somewhat chalky in some specimens. The slender tube also 

 allies it with that section of the Lucirue which have a produced 

 anal conduit. 



The foot, when exserted, has the ordinary tongue-shaped 

 aspect of most of the minuter bivalves, but that is no proof 

 that it has not the singular tubular structure characteristic of 

 the Luciruse, as even in the type L. borealis and in L. rotun- 

 data, both of which beyond doubt have the true Lucinidan foot, 

 it shows no trace of the singularity when protruded, probably 

 from being inflated with water to produce tension. It is only 

 when the animal is killed and opened that the curious con- 

 figuration of the pedal organ is seen. We do not mean to say 

 that Turtonia is a true Lucina, or even one at all, but merely 

 mention these facts, which may have the value they deserve. 

 But we will endeavour to obtain this animal. All these con- 



