MONOGRAPTUS. 



383 



vi.sioiia], iiotliiug l)ut small distal fiagiiieiits of that species having been fignred 

 from Boliemia or Gotland. The characters of the mature thecne are, however, 

 siifRciently distinctive to make it certain that the British form is at any rate a 

 near ally of Perner's species, to which it is for the present referred. 



Horizon and Localities. — Lower Lndlow Shales (zone of M. Nilaaoiii). 



Long Mountain District : Old Dingle Mill. 



Associates, etc. — One specimen alone is known up to the present; it was 

 found in the zone of M. Nllssoni, associated with Moiiog. Nilssoni and M. rariaiis. 



Collect ivu.—Vvot ^y. W. Watts. 



Monograptus '/. ultimus, Perner. Plate XXXV^II, figs. 14 a — (/. 



1899. Monoijraplvs nlthnus, Periier, Etudes sur les Graptolitt'S de Buhciiie, \>i. iii, stct. h, p. 13, 

 text-figs. 14 a, h, pi. xvi, figs. 4, 5, 11 a and h. 



1900. Mo7iO(jra2'tus tdiimvs, Wood, Quart. Jouni. Gfol. Soc, vol. Ivi, p. 461, text-tig. 13, pi. xxv, 

 fiffs. 9 a and 9 b. 



Fias. 253 a — c. — Monograidus cf. ulti- 

 9ui(s, Perner. 



Polypary small and slender, with slight ventral curvature at the proximal 

 termination, not exceeding 2 cm. in length and widening gradually to a 

 maximum breadth of about 1 mm. Thecaj twelve to eleven in 10 mm., 



the adult ones having a length of I'G mm., 

 three to four times as long as wide, with 

 slight tendency to curvature in their walls, 

 and overlapping one-half their length ; ave- 

 rage inclination oO°- — 40°. 

 Descrijjtlon. — The polypary in M. cf. ultiiiins 

 is characteristically small and narrow, and the 

 ventral curvature is confined to the proximal ter- 

 mination in the immediate neighbourhood of the 

 sicula. 



The sicula itself is conspicuous, about 2 mm. 

 in length, reaching to the level of the second thecal 

 aperture ; it is about five times as long as wide. 



The thecas are somewhat peculiar; they are 

 rather closely set, and though when in relief they 

 may appear to approximate in type to those of 31. 

 dahius, when compressed they often show slight 

 indications of ogee curvature in the walls ; it is possible, therefore, that the axis of 

 the theca was not perfectly straight, and that in this case we are dealing with 

 a type of theca showing an approximation to that characteristic of the M. vomerinus 

 grou}). The direction of the apertural margin also varies somewhat, showing at 



51 



a. Complete specimen, natural size. 

 Figured, Quart. Journ. Geol. Soc, 

 vol. Ivi, p. 402, fig. 13. Kosof, 

 Bohemia. Coll. Lapworth. 



6. Proximal end, showing sicula. En- 

 largement of part of PI. XXXVII, 

 fig. 14 a. 



c. Distal thecas. Enlarge ment of part 

 of PI. XXXVII, fig. 14 (L 



