184 Reports & Proceedings — Geological Society of London. 



Inoceramus group, and bears a row of areal ligament pits. The Lias, 

 or at least the Lower Jurassic, is a weli-defined formation in New 

 Zealand, where it overlies the Trias, and in no way resembles the 

 Annelid Beds. 



He felt much interest in the fact that Dr. Bather bad determined 

 the scanty crinoid remains that be collected in the Kaibiku Beds as 

 rather of Upper than of Middle Triassic age. All evidence that these 

 deposits were Permian or Lower Trias seemed now entirely removed. 



2. " The Triassic Crinoids from New Zealand collected by Mr. C. T. 

 Trechmann." By Francis Arthur Bather, M.A., D.Sc, F.R.S., F.G.S. 



The specimens are all from the Kaihiku Series, and comprise : 



(1) an Entrochus from near Nelson, with a broadly waved suture: 



(2) a rock-fragment from the Hokanui Hills, containing imprints 

 of columnals and brachials representing two genera : namely, («) an 

 Entrochus with ridges of the joint-face arranged in pairs separated 

 by shorter ridges ; (b) an Isocrinus, of the group of I. dubius 

 (Goldfuss). Comparison of the three new species based on all these 

 remains with the Triassic crinoids described from Europe and especially 

 with those from North America, leads to the conclusion that they are 

 of Upper Triassic age. They bear, however, no resemblance to the 

 Upper Triassic crinoids from Timor, which the author has in hand 

 for description. 



3. " On a Spilitic Facies of Lower Carboniferous Lava-flow in 

 Derbyshire." By Henry Cruden Sargent, F.G.S. 



The igneous rocks of Derbyshire form a basic series, consisting 

 mainly of lavas and sills, hitherto classed as olivine-dolerites and 

 basalts, often associated with tuffs and agglomerates. All these rocks- 

 occur in Lower Carboniferous strata. The lavas were submarine and 

 contemporaneous. 



Specimens of the lavas from certain localities exhibit a trachytic 

 structure, and possess affinities with both spilites and mugearites. 

 These specimens are all intensely decomposed, felspar being generally 

 the only original mineral that is determinable. The alkali content 

 sometimes exceeds 7 per cent, potash being always important and 

 sometimes predominant. The felspar species are oligoclase and 

 orthoclase, with generally a more basic plagioclase subordinate. 

 Emplacement by alkali-felspar frequently occurs. 



Field evidence shows that these spilitic rocks, as a rule, underlie 

 the basalts. A gradation may be traced between the two extremes 

 of the series. 



It is suggested that the whole series has been derived from a common 

 magma of normal basaltic type, and that, by the upward passage of 

 gases through the magma, a relative concentration of the alkalies took 

 place in its upper part, which was the earliest erupted. 



It is further suggested that the intense decomposition of the spilites 

 is a case of auto-metamorphism, due to retention of volatile con- 

 stituents resulting from the physical environment of a submarine flow. 



An analogue to the radiolarian cherts and jaspers, generally 

 associated with spilites in other localities, is found in Derbyshire, in 

 the quartz-rock and other siliceous rocks that frequently occur in 

 proximity to volcanic vents. 



