Article: Some diplograptids from the British Lower Silurian
Diplograpids (seven species and nine subspecies) are described from various localities in the Lower Silurian of Great Britain, ranging in age from the zone of Monograptus cypftus to that of M. turriculatus. The study centres about Glyptograptus tamariscus (the genotype). From the time of its origin in the zone of M. cyphus, G. tamariscus displays considerable diversification along a number of different evolutionary lines. Other diplograptids which have some general similarity to G. tamariscus are also described, but they appear to be unrelated to it. The new forms described are Glyptograptus tamariscus distorts, G. tamariscus varians, G. tamariscus angulatus, G. tamariscus acutus, Climacograptus tamariscoides, C. tangshanensis linearis, G. enodis enodis, G. enodis latus, G. elegans and C. alternis.