IN THE LOWER CARBONIFEROUS SERIES OF SCOTLAND. A473 
clustered together, there is an entire absence of body-segments, tail- 
spines, or appendages. 
Affinties and Differences—The backward prolongation of the 
lateral margins, the absence of the additional carapace-ridges, and 
other minor features at once distinguish A. Macconochi from 
A. Woodwardi. 
In the serrate and crenulate lateral margins the present species 
resembles A. Grossarti and A. dubius. It differs from the first of 
these, however, by the posterior extension of the central ridge of the 
carapace, the presence of supplementary ridges, and the strongly- 
marked cervical furrow ; but, like A. Grossarti, it has spines at the 
anterior angles of the carapace. 
There is a marked similarity between A. Macconochit and 
A. dubius, Prestwich, in the division of the carapace into two parts 
by the strongly marked cervical groove, the continuity of the 
central ridge, the presence of supplementary ridges (or rather 
furrows in A. dubius), and the serration or crenulation of the entire 
lateral margins. On the other hand, in A. dubius the anterior 
angles of the carapace are not produced into spines, and the 
incuryed posterior angles of A. Macconochii are absent. 
In A. Russellianus, Salter, the form of the carapace is quite dif- 
ferent, as also is the character of the rostrum, from what we find 
them in the species under consideration. ‘The cervical furrow in 
the latter is continuous, and not represented by a row of deep 
punctations. It, however, resembles A. Russellianus in the serrated 
lateral margins. 
It is hardly necessary to compare our form with A.? gracilis, 
Meek and Worthen, although it will be seen that the latter differs in 
the truncation of the carapace before and behind, the small part of 
the lateral margin which is serrate, in the absence of supple- 
mentary ridges, &c. 
Horizon and Locality. From a Cement-stone on the Tweeden 
Burn, near the head of Tweeden Plantation, by New Castleton, 
Roxburghshire. Cement-stone group of the Lower Carboniferous 
series. 
Coll. Geol. Survey of Scotland. 
Collector. Mr. A. Macconochie, after whom the species is named. 
EXPLANATION OF PLATE XXIII. 
Fig. 1. Dithyrocaris testudineus, Scouler. Two half carapaces in apposition, 
and the outline restored: nat. size. Tweeden Burn, near New 
Castleton. 
2. Dithyrocaris, sp. ind, Abdominal somites, tail-spines: nat. size. Liddel 
Water, near ditto. 
. Dithyrocaris, sp.ind. Abdominal somites &c., crushed sideways, with 
an epimeral border and the central tail-spine: nat. size. Liddel 
Water, ditto. 
4. Anthrapalemon Woodwardi, R. Eth. Showing the general characters 
of the species, including the eyes (restored) and the first pair of 
chelate appendages: X 7. Liddel Water, near New Castleton. 
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