THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
221 
The transition to aggregates of the third order proceeds 
in the same unobtrusive manner. The variously formed out¬ 
growths from the sides of a frond of Rhodymenia paJmata 
exhibit the beginning of such a tendency, which becomes 
more marked in Delesseria sanyuineci; but the sea-weeds, 
though nearly approaching it, do not present us anywhere 
with a complete tertiary aggregate. This we shall meet with 
first among the Jungermanniaceae, as, for instance, in J. 
asplenioides, and more decided examples are abundant in the 
ordinary type of Mosses. Take the common Hypnnin 
triquetrum; we see a definite erect stem, regularly furnished 
with foliar expansions each of which presents the characters 
of a perfect aggregate of the second order, and these by their 
definite subordination to the stem make the whole a compound 
individual of the next highest order. The groups in which 
this is predominant form the classes called Acrogens or 
Cormophyta. 
So far we have considered only the cryptogams. The 
extension of the theory to the Pliaenogams, and some 
important deductions from it, form the subject of the next 
chapter. 
THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
BY BEEBY THOMPSON, F.G.S., F.C.S 
PAKT II. 
Palaeontology. 
(Continued from page 122.) 
In drawing up the list of fossils below, I have consulted 
the following works and papers; and where the record is of 
a form I have not found myself the authority for it is quoted. 
1860. —Aveline, W. T., and Trench, Richard. Geology 
of parts of Northamptonshire. Memoirs of Geological 
Survey. (Description of quarter sheet, No. 58, S.E.) 
1861. —Aveline, W. T. Geology of parts of Northamp¬ 
tonshire and Warwickshire. Memoirs of Geological Survey. 
(Sheet, No. 53, N.E.) 
1872. —Beesley, Thos. A Sketch of the Geology of the 
neighbourhood of Banbury. Paper read at the annual 
meeting of the Warwickshire Naturalists’ and Archaeologists’ 
Field Club, March 5, 1872. 
1875. —Judd, Prof. J. W. The Geology of Rutland, and 
parts of Lincoln, Leicester, Northampton, Huntingdon, and 
Cambridge. Memoirs of Geological Survey. 
