114 REPORT 1861. 



" The English strata, on the other hand, rarely contain entire insects ; generally 

 there are only some part of the wings, abdomen, and thorax, and these besides are 

 usually imperfect. Hence it appears worthy of consideration whether the insects 

 of the English strata do not convey the inference that, through the agency of stoims 

 and other commotions, the fragments were tossed about a long time before they 

 found a resting-place. 



" There is the less to be said against this conjecture, as the wings of insects 

 (which form by far the larger part of the English entomological fossils) are almost 

 indestructible in water. I have kept the wings of dragon-flies in water for years 

 without observing the slightest change in their texture. 



" From a careful study of the fossils of Solenhofen, and a comparison with the 

 published figures of the fossil insects of England, I have deduced two conclusions : — 



" First, that the two faunae are very closely allied, and possibly some species in 

 both formations are identical. 



" Secondly, that the fauna3 of Solenhofen and of the English strata are not only 

 quite distinct from the existing fauna, but also from those of Aix, of the Rhenish 

 peat-deposit of (Eningen and Kadoboj, and from that of amber, differing not only 

 m species but in genera. 



"Almost all the Solenhofen insects will necessitate the construction of new 

 genera, which, however, wiU often furnish connecting links between some of our 

 existing genera. 



" In reference to the Odmiata (dragon-flies), which fonn so large a portion of the 

 insect fauna of the Solenhofen strata, and pieces of the wings of which seem not 

 uncommon in the English strata, we iind a remarkable contrast between the faima 

 of the English secondary sti-ata and the fauna of ffiuingon and Radoboj. Whereas 

 here, as also in the Rhenish peat, lai-vaa and pupfe of Lihclhdce are found in great 

 numbers, many often lying together, the perfect insects beino' proportionally scarce ; 

 in the Solenhofen and Eichstadt deposits Libcllulce are precisely the most plentiful 

 specimens (forming |rd of all tlie insects.), and on the other hand, up to the present 

 time not a single larva or pupa has been foimd. 



" The absence of larvre in the Solenhofen strata may be accounted for by the 

 supposition that the waters on whose shores these strata' were deposited were salt ; 

 just as at the present day numerous Odonata are buried in the sands on the shores 

 of the Baltic, although their larvas do not live in that sea. The deposits of Oilningen 

 and Radoboj, on the other hand, we must conclude were made in fresh water." 



On the Old Red Sandstone of South Perthshire. 

 By Professor HARKirass, F.B.S., F.G.S. 



At the Bridge of Allan, which is situated immediately on the north side of the 

 fault separating the coal-field of StirUng'shire from the Old Red Sandstones on the 

 noi-th thereof, tliere are seen, on tlie side of the hill near the well, conglomerates 

 which are principally made up of fragments of trap, and these, in their higher 

 beds, have grey sandstones intercalated with them. These grey sandstones, on 

 ascending the series, occur exclusively; and they are well seen at Wolfs Hole 

 quai-ry, dipping at 20°N.W., being capped by trap. Here, in the grey sandstones, 

 the remains of Pteraspis rostratus have been found, and in the same strata portions 

 of a Cephalaspis also occur. 



A section shovnug the arrangement of the deposits which succeed these grey 

 sandstones may be seen in the course of the Allan to beyond Dumblane. A con- 

 tinuation of this section may bo obtainetl in the course of the Teith ; and the river 

 Keltic, which flows into the Teith about .3 miles below Callander, furnishes the 

 series of deposits which join those of the Teith. Collectively a section may be had 

 showing the natm-e anA the arrangement of the deposits which occupy the area 

 between the fault alluded to as occurring on the south, and the metamorphic rocks 

 of the southern flanks of the Grampians. 



This section exhibits a trough on the margins of which conglomerates occur, 

 these forming the lowest strata. 



To these conglomerates succeed deposits which contain Pteraqns and Cepha- 

 laspis, consisting of grey sandstones. Pui-ple strata occur above these, to which 



