Vol. 56.] FORMATION AND ITS GRAPTOLITE-FAUNA. 483 



opportunity of collecting many specimens from his type-locality of 

 Borek, and I feel no doubt that our English species agrees in 

 every particular with the Bohemian form. It is probably also 

 identical with the Swedish form Monograptus Nilssoni, described by 

 Tullberg, 1 though in his plate the whole polypary is not figured and 

 the thecae are shown as rather more closely set. 



The nearest relation of M. Nilssoni is undoubtedly the so-called 

 Cyrtograptus Carruthersi of the Upper Wenlock Beds, fragments of 

 which are indistinguishable from similar fragments of M. Nilssoni 

 when both are similarly preserved. 



Range. — In Britain there is little doubt that M. Nilssoni, in 

 its characteristic form, is confined to the Lower Ludlow Beds, 

 outside of which I have myself never found it. I have collected it 

 at Borek (Bohemia) in association with the Ludlow forms M. colonus 

 var. and Retiolites spinosus. 



Foreign Localities. — Bohemia (Borek, Vyskocilka, etc.) ; 

 Scandinavia (Hjontarod, Knutsdorp, Tibarod, etc.) ; Saxony ; 

 Thuringia ; Harz Mountains ; Graptolithengestein (Ronneburg and 

 Grafenwerth) ; France (Languedoc, Normandy, Britanny, etc.). 



British Localities. — Ludlow district (Elton Lane, Elton- 

 Ludlow Road, Adferton, etc.) ; Builth (R. Irfon, etc.); Long Moun- 

 tain (Old Dingle Mill, etc.) ; Montgomery Road ; Lake District. 



Associates. — M. bohemicus, M. colonus and its variety com- 

 pactus, M. varians and its variety pumilus, M. Moemeri, M. dubius, 

 M. uncinatus var. orbatus and var. micropoma, etc. 



Monograptus bohemicus (Barr.). (PI. XXV, figs. 27 a & 27b 

 and text-fig. 25, p. 484.) 



1850. Graptolithus bohemicus, Barrande, ' Graptolites de Boheme ' p. 40 & pi. i, 

 figs. 15-18. 



Polypary gracefully bent, the proximal part being curved 

 almost into a semicircle, while the distal end has a broader sweep, 

 becoming eventually almost straight. Fragments 7*5 to 10 cm. (3 to 

 4 inches) long are found, so that the polypary must have reached a 

 considerable length. The width increases gradually from *36 mm. 

 (•01 4 inch) at the proximal end to 2 mm. (-08 inch) distally. The 

 virgula projects slightly at the distal end. 



Proximal Extremity. — Sicula very characteristic, about '85 

 to 1 mm. (-03 to -04 inch) long, and *32 mm. (*012 inch) wide at 

 the aperture, so that it is only 2j to 3 times as long as wide. 

 The apex does not quite extend to the level of the aperture of the 

 first theca, which' is inclined to the sicula at an angle of about 

 45°. Aperture furnished with a long and stout spine. 



Thecae. — Twenty-seven to twenty-three in the inch (eleven to 

 nine in 1 cm.), occurring on the concave side of the polypary. 

 Thecse in contact merely, or with a slight overlap in the more distal 

 thecse, inclined to the axis at an angle of about 30° to 35°. They 



1 ' Skanes Graptoliter' pt. ii (1883) Sver. Geol. Undersokn. ser. C, no. 55, 

 p. 17 & pi. i, figs. 31-32. 



