ANTHRACOMYA. 85 
Myadz ; and under his observations on Anthracomya senex says: ‘* We cannot get 
at the interior, but there is not much doubt there is a pallial sinus; and there 
were probably long siphonal tubes covered by a thick epidermis, the animal 
burrowing in the mud as most Myade do.”?! It is difficult to see why such a 
relationship should be so strongly insisted upon in the absence of direct evidence, 
but Mr. Salter held the view that the Coal-measures were a marine deposit, 
consequently the paleontology had to be fitted in to suit this opinion. 
The characters on which Mr. Salter probably most strongly relied for the 
reference of these shells to the Myade are the occasional gaping of both ends 
(but this is not at all of constant occurrence, even in the same species) and the 
\/-shaped markings on the type specimen of Anthracomya senex. He says, speaking 
of the shells for which he is proposing a new name (p. 230, op. cit.): “ For these 
the discovery of a common character in the epidermis at length enables me to 
propose a generic name ;” but beyond stating that the epidermis is wrinkled, he did 
not in any way say what this common character was. These markings in A. senew 
are toa large extent accidental and not specific, and this fact will be further noted 
under observations on this species (p. 111). But a\-shaped arrangement of the 
periostracum is to be found in some members of the Unionide’ from abroad, and 
is therefore in no way peculiar to the burrowing Myacide. The absence of a 
pallial sinus, the simple Unio-like type of hinge-line, erect external ligament, 
absence of an internal cartilage, the position and shape of the adductor muscles, 
and the thickened periostracum, all point rather to a connection with the 
Unionide. In common, however, with Carbonicola, Anthracomya has the 
accessory adductor scars situated above and posterior to those for the anterior 
adductors, and not, as in recent Unionide, below and posterior to them. 
In shape the Anthracomyz approach the genus Tridina (Mutela) but are 
distinguished by the absence of the multidenticulate hinge. 
There is little evidence to be obtained in favour of the view that the Anthra- 
comya were burrowers. They are very seldom found at right angles to the 
stratification of the beds in which they occur, but nearly always he parallel to 
them; and, further, they are always associated with byssiferous Naiadites which 
could not have lived buried in the mud. 
All the early writers referred the shells, subsequently grouped under the name 
Anthracomya, to Unio, Ludwig recognising the close resemblance to Anodon by 
referring several forms to this genus, with which there are strong resemblances in 
shape and hinge-structure ; but there are certain marked differences, the umbones 
1¢*Mem. Geol. Surv. Great Britain;’ ‘Iron Ores of Great Britain,’ part iii; ‘Iron Ores of 
South Wales,’ 1861, p. 231. 
2 For example, the species named Unio Vignonianus, U. Kleinianus, and Anodonta rugifera in 
the Collection of recent shells in the Natural History Museum, South Kensington. 
