ii6 The American Geologist. February, i903. 
In recent Terchratulina caputserpcntis or T. septcntrion- 
af'is, the punctae may be seen on the inner and outer side of the 
shells. On the inner side, everywhere excepting about the teeth 
and their sockets, the rostral and muscular region. In no 
brachiopod have I seen punctae over the area of the muscular 
insertions. 
In recent Liothyris vitrea the shell is very thin and is abun- 
dantly punctate on the inside as well as the outside except in 
the same regions as those mentioned for TerehratuUna. 
In thick shelled Terchratnla, as T. grandis of the Cor- 
alline Crag, Suffolk, England, or in T. harlani of the Upper 
Cretaceous of New Jersey, the inner layer has no punctae 
throughout the thicker posterior parts of the valves. The 
thicker, or the older the shell, the more restricted are these 
punctae to the lateral and anterior margins. 
In the strophomenoids, the regularly disposed punctae are 
well developed in the outer layer, but on the inside, very rarely 
if ever. However, in these forms, much of the anterior half of 
the inner sides of the valves are covered with more or less 
large pustules or even blunt spines. These may be regularly ar- 
ranged in radial lines or irregularly scattered. Some of these, 
and especially the lower and smaller pustules, are plainly per- 
forate. Apparently a single comparatively large coecal pro- 
longation passed through these pustules and was branched 
toward the outer side in passing into the punctate outer layer. 
Undoubtedly in many cases these coeca became functionless 
and then the youngest or innermost shell layer over these pus- 
tules are not perforate. In nearly all strophomenoids the pus- 
tules are most abundant and perforate just inside the outer 
margin. The occurrences just described may be seen in the 
Lower Silurian Rafinesqnina alternata. Upper Silurian Lep- 
taena romboidalis, Devonian Stropheodonta calvini, S. arcuata, 
or Carboniferous Chonetes graniilifer and Productella pyx- 
idata. 
These phenomena I find noted by Sharpe as long ago as 
1847 (Qii^i't- Jour. Geol. Soc. London, IV, p. 67, foot note). 
He states that ''an inner layer of unpunctated shell lining an 
outer punctate layer is of common occurrence among tlie 
Brachiopoda." Sharpe observed this in- Orfhis, Leptacua, 
Prodiictns, Choncics, Crania, Tliccidca and Terchratnla. In 
