NO. 1596. DALMANELLAS OF THE CHEMUNG— WILLIAMS. 47 
nant, and in the upper part of the Cayuta member this form tends to 
throw the maximum width up toward the hinge line to make form 
delta. In only the highest zones are forms epsilon and zeta found. 
Striae and lines—In their definition of the genus Dalmanella, 
Messrs. Hall and Clarke speak of the surface as “ covered with fine 
rounded striz.” ¢ 
In this, as in other cases of desertiatine literature, the term stria 
(pl. strive) is often used in such a way as to indicate that the author 
refers to linear markings raised above the general surface and does 
not mean incised narrow grooves. In discussing the surface mark- 
ings of such shells? it is important to distinguish between linear 
markings raised above the surface and those depressed below the 
surface. — 
From its etymology the term stria properly means a depressed 
furrow or channel, but for the elevated linear markings the term 
line is more appropriate. In this paper line (and not stria) will be 
used wherever the markings indicated are raised above the surface, 
and stria will be used only where a groove between two lines is meant 
or where the linear markings are actually incised below the general 
surface of the shell. 
The radiating lines increase in number with growth of each in- 
dividual by implantation of secondary lines on the sides of the 
primary lines; the primary line is generally retained as primary in 
the fascicle of secondary and tertiary lines out to the front of the 
shell. 
Upon the initial entrance of the genus into the province, a primary 
radiating line occupies a median position at the beak of the brachial 
valve in the smaller specimens and retains its dominance there to 
the front. On passing upward in the series as the size increases the 
effect is most pronounced upon the central part of the shell. The 
implantation of secondary and then of tertiary lines takes place 
higher. up teward the beak in the later forms, resulting in a fuller 
fasciculation of the lines at corresponding distances from beak than 
in the smaller species. 
In this acceleration of growth the central line becomes dichotomized 
early in growth so that in most specimens of D. tioga, D. elmira 
and later forms the dominance of a median central line in the brach- 
ial valve is lost sight of and a depressed stria is dominant from very 
close to the beak all the way to the front in the middle of the sulcus 
of the brachial valves. This difference in the arrangement of the 
lines in the central fascicle of the brachial valve, instead of being 
4Hleventh Annual Report State Geologist, New York, 1892. Handbook of 
Brachiopoda, Pt. 1, p. 270. 
5 See Sardeson. The Galena and the Maquoketa Series. Pt. 3. Am. Geol., 
XIX, 1897, pp. 91-111. 
