Second report onthe Copepoda of the Irish Atlantic slope

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 Excerpt: ...of confusion between this and the next species, Scottocalanus persecans, which closely resembles it, but can at once he separated by its rounded fifth thoracic segment in both sexes, whereas in S. securifrons the fifth segment is pointed laterally in both male and female. Scott, in his original description (1893), has indicated most clearly the female of the present species, his figures, showing the fifth thoracic segment with acute lateral terminations, and the short abdomen with large genital segment partially overlapping the second abdominal segment ventrally, being quite unmistakable. His figure of the male, however, undoubtedly refers to the following species, S. persecans, and in the type specimens in the British Museum the females of both species are bottled together under the name of Scolecithrix secunfrons. Canu (1896) was the first to rediscover the species, in the "Caudan" Collections from the Bay of Biscay, and in his notes upon it expressly states that he uses the name S. securifrons for the form with the acute fifth thoracic segments. It has subsequently been recorded by Dr. Wolfenden, who places it in the genus Lophothrix, and Prof. G O. Sars, who has however, as he has been good enough to inform me, described it as a new species under the name Scottocalanus acutus, while using Scott's name securifrons to designate the species with the rounded fifth thoracic segments. Occurrence.--This species is very characteristic of deep-water townettiugs off the west coast of Ireland. It occurred on every station except S.R. 140, usually in the deepest nets, though on station S.R. 197 it was taken at 100 fathoms. It seemed to be most plentiful at about 700 fathoms. Scottocalanus persecans (Giesbrecht). Scolecithrix secunfrons, T. Scott, 1893, pa...