Analysis of 17 samples for both major and trace elements reveals that, unlike most other Tertiary composite intrusions, the Creag Dubh sheet possesses silicic margins and a doleritic centre. The two rock types grade together rapidly without chilling at the upper and lower internal contacts. However, there is evidence for mixing of the two magma types prior to or during emplacement with the production of limited amounts of intermediate hybrids. The central dolerite appears to be later than the marginal felsites which in places back-vein the dolerite. The sequence of intrusion is tentatively related to the upward draining of a strongly zoned magma chamber.

Although a root system has been discussed for the blastoid Pentremites, no cirri have been reported and no photographic illustrations have heretofore been given of the complete animal. Two specimens with complete stems with sporadic cirri along the entire length and distal attachment cirri, and one specimen with a long portion of stem, a few cirri and spiracle covering plates preserved in place, are reported herein. All three specimens are from the Fraileys Formation, Hombergian Stage, Chesterian Series, Upper Mississippian of southern Illinois, U.S.A. (Zone E1, Pendelian Stage, Namurian Series [A], Upper Carboniferous). An eleutherozoic or free life style is postulated.

K—Ar age measurements on Esquibel Island, southeastern Alaska yield a minimum age of about 433±3 Ma for the Zone of Monograptus cyphus of the Lower Silurian. An age of approximately 435—437 Ma is estimated for the Ordovician—Silurian boundary.

Phacops turco aff. praecedens Haas, from the Devonian (Eifelian) of Morocco, varies in the type of lens packing in the eye. Cubic close packing in trilobite eyes is described for the first time.

A temporary exposure of the Abbey Shales at Vernons Lane, Nuneaton, yielded a lower Paradoxides davidis fauna. The absence of the upper Paradoxides davidis fauna confirms the southerly overstep of the Abbey Shales by the overlying Mancetter Grits and Shales. Well-preserved fragments of Clarella impar (Hicks) and Tomagnostus gracilis (Illing) are illustrated.

Textural and chemical data on altered ‘spinifex’ (i.e. quench texture) ultramafic rocks from Corsair, near Kalgoorlie, Western Australia, have indicated that serpentinisation of contained olivine phenocrysts involved a volume increase of some 60%, due to the addition of both SiO2 and H2O.

Evidence is presented for Liassic (Toarcian) faulting at Watton Cliff in coastal W Dorset. This movement is inferred from the abrupt changes in thickness of the Junction Bed and contiguous strata given that the contact with the overlying shale and clay is horizontal. Further evidence for synsedimentary movement is manifested by the presence, in the palaeofault zone, of numerous calcilutite-filled fissures penetrating a coarser, more sandy matrix. These neptunian dykes and sills contain abundant ammonites of the middle to late Toarcian, presumably the time of fault movement. This onshore Jurassic palaeofault broadens the known extent of such features from Sutherland (Brora—Helmsdale Fault) and Yorkshire (Peak Fault) to include southern Britain.

A new Ordovician stromatoporoid species, Labechia aldonensis, is described and illustrated from the Stinchar Limestone (Barr Group) of the Girvan District, Scotland.