484 



MISS E. M. E. WOOD ON THE LOWER LUDLOW [May I9OO, 



Fig. 25. — M. bohemicus 

 (Barr.) x5. 



are short broad tubes, only about 2 to 3 times as long as wide ; the 



outer wall is constricted where it is 

 in contact with the theca below, but 

 convex above, the aperture being 

 concave and fairly wide, and provided 

 with a small denticle. 



There are few species so readily 

 recognizable as this one, and it has been 

 correctly identified by most observers, 

 Nicholson, however, confused it with a 

 Llandovery species which has a strong 

 convex curvature. Prof. Freeh regards 

 Monograptus bohemicus as a ' doubtful 

 species ' resembling his Linograptus 

 Nilssoni. Barrande reckons only twenty 

 thecae to the inch in his description of 

 M. bohemicus (though in his figures there 

 are twenty-three), but in all the 

 English specimens there are as many 

 as twenty-seven at the proximal end, 

 and in none are there so few as twenty, 

 even in the adult parts. The sicula 

 and its position with regard to the 

 first theca were first figured by Tull- 

 berg, and are very characteristic of this 

 species, being quite different from that 

 of M. Nilssoni. The general form of 



the polypary varies somewhat at different localities : thus, in the 



Ludlow district the specimens are small and strongly curved ; 



while at Builth they often reach a considerable length, and the 



distal part is almost straight; in the Dee Valley they are long, 



but curved throughout. I do not consider, however, that these 



variations in shape are worthy of varietal names. 



Foreign Localities. — Scania (Rostanga, Ask, Billinge, Pu- 



gerup, Rbfvarekulan, Harlosa, Heinge, Djurrod, Tosterup, Tolonga) ; 



Bohemia (Butowitz, Vyskocilka, Kozel, Kosor, Kuchelbad, etc.) ; 



Thuringia ; Harz Mountains ; Graptolithengestein (Kunzendorf, 



Rexdorf , Grafenwerth) ; Polnisches Mittelgebirge ; France (Lan- 



guedoc, Ardennes, Normandy, and Britanny). 



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



Evenhay Lane, Elton-Ludlow Road, etc.) ; Long Mountain (north 



side) ; Builth district (Aberedw Hill, River Irfon, etc.) ; Lake 



District (Helm Knot). 



Horizon. — M. bohemicus ranges throughout the greater part 



of the Lower Ludlow, but is most characteristic of the zone of 



M. Nilssoni. In Sweden, Bohemia, etc., it occurs in the Cardiola- 



heds. 



Associates. — M. Nilssoni, M. scanicus, M. chimcera, M. colonus, 



M. varians, M. tumescens, M. uncinatus var. rnicropoma, and Retio- 



lites spinosus. 



£ = Di8tal theca ; from the 

 River Irfon, Builth. 



b = Proximal extremity, with 

 sicula; from the Elton- 

 Ludlow Road. 



c = Distal extremity ; from 

 the Elton-Ludlow Road. 



