Om Skånes brachiopodskiffer 
97 
The ontogenetic development of D. eucentrus is described on p. 64—67 and 
is closely allied to that of Dalmanites socialis Barr. The development of head is 
shown on fig. 10, p. 59. A tail (pi. I, f. 23) belonging to the nepionic stage has 
more of pleurae than adult specimens which depends on the fact stated by Richter 
that the posterior pleurae are tending to fuse along the axis. 
A few of larval stages of the same species are found. The youngest of them, 
an anaprotaspis Beecher, is figured on pi. I, f. 24. 1 
D. eucentrus belongs perhaps to that primitive section of the Dalmanites group 
which has been termed Dalmanitina Reed, but the strange alternation of the 
appearing of the named two species in the succeeding life-zones suggests more that 
D. eucentrus is an immature stage of D. mucronatus and a result of retardating 
external circumstances after the ceasing of which a perfect development has taken 
place again. 
Horizons. Dalmanites eucentrus occurs in the lower part of the Brachiopod 
beds (subzone of D. eucentrus). 
D. mucronatus, however, is met with already in the zone of Staurocephalus 
clavifrons , but is lacking in the entire subzone of D. eucentrus but appears again in 
the upper part of the Brachiopod beds, subzone of D. mticronatus. 
On p. 71 — 75 a short reference is given of the statements concerning the distri- 
bution of D. eucentrus and D. mucronatus outside Sweden. As to the English 
works it seems to us as if two species are met with, closely allied to the above- 
mentioned ones, D. mucronatus being most allied to the species spoken of by 
Bigsby 1868 — Marr & Nicholson 1888 (p. 72 — 73 above) and D. eucentrus to 
that mentioned by Salter 1853 — Marr 1907 (p. 73 — 75 above). The specimen 
figured by Salter (1864 pi. IV, f. 11 — 12) resembles D. eucentrus very much, but 
the anterior half of the pleurae — not the posterior one as in our species (see 
fig. 11, p. 60) — widens outwards while the broader posterior part decreases in the 
same direction. 
In the area of Christiania, Norway, D. mucronatus occurs in the Meristella 
crassa beds of »Brachiopodskiffer »-facies. But in the same horizon there is found 
a very differing species that is not kept distinct from D. mucronatus. It may be 
described as follows: 
Dalmanites Kiaeri n. sp. 
Pl. II, f. 23. 
Outline of head subtriangular. Length of glabella about 1,5 times the width and accordingly 
more uniform of width than on the Swedish species. Lateral furrows broad and almost straight 
with shallow interior ends. Frontal lobe almost as long as wide, circular of outline and is before 
the median pit ornamented with coarse tubercles. In a transverse section across the anterior 
1 Another anaprotaspis described on p. 65 and figured on pl. I, f. 25, is found in the subzone 
of B. eucentrus but is referred to the genus Proetus. 
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