MONOGRAPTUS. 



463 



Figs. .'$21 a and b. — Monograptus knoclc- 

 ensis, sp. nov. 



S* 





- 



of 1*5 mm. opposite the thecal apertures. Thecae seven in 10 nun., with the 

 apertural region coiled tightly upon itself almost in a horizontal plane so 

 that the apertural margin faces the adnate region, the lobe thus formed 

 involving fully one-half the thecal length, and occupying two-thirds of the 

 breadth of the polypary. 

 Description. — The polypary is only known in a fragmentary condition, but is 



sufficiently characteristic to render its separation 

 from all other Monograpti easy. It was noted long- 

 ago by Nicholson and Marr as a new species, but 

 never described by them. The total breadth of the 

 polypary including th ) thecal lobes is 1/5 mm., but 

 elsewhere the width doss not exceed "5 mm. 



The thecse are distant, their ventral walls show 

 concave curvature, and the lobed apertural region is 

 disproportionately large, and is so closely coiled 

 upon itself in a horizontal plane that the apertural 

 margin lies parallel to the dorsal wall of the poly- 

 pary. In the reverse aspect the lobes are practically 

 concealed so that it is clear that there is much 

 torsion of the whole apertural region of each theca, 

 and even in the obverse aspect the same is suggested 

 by the variation in the position of the lobe. 



Affinities. — The isolation of the theca, and the 

 unusually large size of the lobed apertural region render the species separable 

 from all others in the group to which it belongs except M. lobiferus itself, and from 

 this its distant lobes are sufficient to distinguish it. 



Horizon and Locality. — Tarannon Beds (Browgill beds), zone of M. crispus. 

 Lake District : Knock, Edenside. 

 Collection.— Dr. J. E. Marr. 



kL 





'■~ 



a. Distal thecae, showing various appear- 



ances presented by the lobes. En- 

 largement of part of PI. XLVI, fig. 

 8 6. 



b. Counter impression of part of same 



specimen. 



V. (<■) : Monograpti with lobed thecae in which the polypary has dorsal curvature. 



Monograptus Cling ani (Carruthers). Plate XLVI, figs. 11 a—f. 



1868. Graptolithus Clingani, Carruthers, Geol. Mag., vol. v, p. 127, pi. v, figs. 19 a, b. 

 1876. Monograptus Clingani, Lapworth, Geol. Mag. [2], yol. iii, p. 501, pi. xx, figs. 3 a — c. 



Polypary several cm. in length, fairly robust, arcuate or straight distally, with 

 broadly recurved proximal portion, widening rpiicklyfrom an initial breadth 

 of "8 mm. to a maximum of about 1*5 mm. Thecaa on the convex margin, 



61 



