The Quarterly journal of the Geological Society of London . in the Woodwardian is a somewhat rigid and very slender form, and is characterizedby the unusual length of the stipes of the 1st order, which aremuch longer than in any form of Dichograptus hitherto stipe must be fully J inch (3*17 mm.) long, and thus what olderauthors would have regarded as the funicle is | inch ( mm.)in length. The two stipes of the 2nd order make with eachother an angle of 105° ; these are rather less than ^ inch in length; Vol. 54.] FAUNA OF THE SKIDD AW SLATES. 485 they fchen dividedi
The Quarterly journal of the Geological Society of London . in the Woodwardian is a somewhat rigid and very slender form, and is characterizedby the unusual length of the stipes of the 1st order, which aremuch longer than in any form of Dichograptus hitherto stipe must be fully J inch (3*17 mm.) long, and thus what olderauthors would have regarded as the funicle is | inch ( mm.)in length. The two stipes of the 2nd order make with eachother an angle of 105° ; these are rather less than ^ inch in length; Vol. 54.] FAUNA OF THE SKIDD AW SLATES. 485 they fchen dividedichotomously,giving rise to theeight stipes of the3rd order, whichmake with eachother an angleof about 70^^These stipes maybe as much as 3inches in length. The whole rhab-dosoma is veryslender, never at-taining a greaterwidth than X-inch (5 mm.). The thecae arenot very clearlyseen, but theyseem to be closelyset, and numberthirty-two to theinch (thirteen in10 mm.). Locality. —Outerside. Pig. 10.—Dichograptus separatus,(coll. Woodwardian Mus.). sp. [Nat. size.] Genus Tetragraptus, Salt. (/) Tetragraptfs quadribrachiattjs (Hall). 1858. Graptolithus quadrihrachiafus, Hall, Greol. Surv. Canada Rep. 1857, p. 125. 1863. Tetragrapsus crucialis, Salt., Quart. Journ. Geol. Soc. vol. xix, p. 137,fig. 8 6. 1865. Graptolithus quadrihrachiafus, Hall, Grapt. of the Quebec Group, Canada, dec. 2, p. 91, pi. v, figs. 1-5, & pi. vi, figs. 5, 6. 1868. Tetraqrapsus quadribrachiatus, Nich. Quart. Journ. Geol. Soc. vol. xxiv,p. 131. 1875. Tetragraptus quadribrachiatus, Hopk. & Lapw. ibid. vol. xxxi, p. 649 &pi. xxxiii, figs. 9 a &b. Tetragraptus quadribrachiatus (Hall) seems to be abundant inthe Skiddaw Slates. There are specimens of all ages and sizes, butonly a few are sufficiently well preserved to show the characters ofthe thecse; the rest merely show the typical form of the species. The ultimate stipes are generally straight and rigid; they areslender at their origin, and gr
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