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A revised nomenclature and stratigraphical distribution are recorded for species of the spatangoid genera Epiaster and Micraster from the Turonian and Senonian of southern England. Distinguishing characters of the species are summarized, and the names E. michelini, E. laxoporus, M. normanniae, M. decipiens, M. coranguinum simpsoni, and M. westlakei advocated for British material. The old cortestudinarium Zone is here replaced by a lower normanniae Zone, of probable Turonian age, and an upper decipiens Zone, of Coniacian date.

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Nine species of Tretaspis are recognized from various horizons of the Ashgill Series in Wales. Tretaspis colliquia Ingham is regarded as a sub-species of T. moeldenensis Cave. Four populations of Tretaspis are placed in T. moeldenensis (s.l.) and considered to occupy intermediate positions within the plexus connecting T. moeldenensis colliquia and T. m. moeldenensis; for the latter, large topotype samples also give increased knowledge of the fringe characters. T. cf.

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Falloticeras Parona and Bonarelli, 1897 (type species: Ammonites proteus d'Orbigny, 1842) is a diminutive Cretaceous (Middle Albian, dentatus Zone) member of the acanthoceratacean subfamily Mojsisovicsiinae, individuals of which are generally adult at less than 35 mm diameter. The genus is considered to be a micromorph, perhaps a neotenous offshoot of Mojsisovicsia Steinmann, 1881, rather than simply a microconch of that genus. This is suggested by differences in ontogenetic development, relative abundance, and stratigraphic distribution.

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Button-shaped phosphatic microfossils from the uppermost Atdabanian (Lower Cambrian) of the Siberian Platform (middle reaches of the River Lena, Yakutia, U.S.S.R.) are described as Lenargyrion knappologicum n. g., n. sp. The fossils have a mean diameter of about 150 ^m. One side is smooth and slightly convex, the other conical with a flat crest on which are set minute nodes. The internal structure is double-layered: the conical and nodular surfaces are formed by a dense layer capping the more porous core, which contains fine canals.

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The algal tribe Thyrsoporelleae Pia, 1927 (Family Dasycladaceae, Order Dasycladales) is examined in the light of later additions and discoveries. It is considered that the reasons for the earlier grouping are not now valid: Thyrsoporella, Belzungia, Dobunniella, and Placklesia now constitute the Thyrsoporelleae emend.; Dissocladella constitutes the Dissocladelleae trib. nov.; Trinocladus is transferred to the Triploporelleae.

• Read more about A consideration of the tribe Thyrsoporelleae, dasyclad algae

Five species of Lower Cretaceous conifers assigned to the genera Pseudofrenelopsis Nathorst, Frenelopsis Schenk, and Cupressinocladus Seward of the family Cheirolepidiaceae are redescribed and figured with emended diagnoses. Lectotypes of P. parceramosa (Fontaine) comb. nov., P. varians (Fontaine) comb. nov., and F. ramosissima Fontaine are selected from Fontaine's figured specimens in the collection of the National Museum of Natural History, Smithsonian Institution. A specimen of F. alata (K.

• Read more about Some Lower Cretaceous conifers of the Cheirolepidiaceae from the U.S.A. and England

The lower Aalenian (Middle Jurassic) ammonite Bredyia subinsignis (Oppel, 1856) has been investigated at several growth stages and found to be dimorphic. Burtonia crassornata Buckman (1910a), the type species of Bredyia Buckman (19106), is regarded as a junior synonym of Ammonites subinsignis Oppel (1856) as are Hammatoceras newtoni Buckman (1892), H.feugeurollense Brasil (1893), and several species described by Dumortier (1874).

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Dental morphology and tooth succession in Procolophon are described and discussed in detail. Replacement is not alternate; instead, a limited number of teeth are added at the back of the row and lost from the front. It is possible that the teeth of old individuals represent yet another set.

• Read more about Tooth function and succession in the Triassic reptile Procolophon trigoniceps

An ostracoderm fauna which includes Tolypelepis leopoldensis sp. nov., Corvaspis cf. C. arctica Loeffler and Dinely, and ?Kallostrakon sp. indet. occurs 30 m above the base of the Leopold Formation on Somerset Island in the Canadian Arctic Archipelago. Associated ostracods and conodonts indicate a Late Ludlovian or Pridolian age for the ostracoderm horizon.

• Read more about Additional late Silurian ostracoderms from the Leopold Formation of Somerset Island, North West Territories, Canada

Hallucigenia sparsa (Walcott) gen. nov. from the Burgess Shale (Middle Cambrian) is redescribed. It is characterized by an elongate trunk supported by seven pairs of long spines. The trunk also bears seven tentacles with bifid tips and a group of short posterior tentacles. A globular head lacks appendages. Despite certain similarities to the polychaetes H. sparsa is not an annelid. Its systematic position, as well as its mode of life, remain problematical.

• Read more about A new metazoan from the Cambrian Burgess Shale of British Columbia