80 BlUTlSIl GRAJ^TOLITES. 



Dichograptus separatus, Elles. Plato X, figs. 4x1, h. 



1898. Dichoijraptus sejiaratus, Elles, Quart. Jouru. Geol. Soc, vol. liv, p. 484, fig. lO. 



Stipes of first order either equalling in length, or longer than, those of second, 

 but both short compared with length attained by main stipes of third order ; 

 these last are slender and somewhat rigid, 2*5 to 7'5 cm. in length, but 

 never exceed "5 mm. in width. Theca3 ten to twelve in 10 mm., narrow 

 tubes, outer walls three times as long as wide, inclined 20°, and overlapping 

 about one third their length. Apertural margins straight, perpendicular. 



Bescriptlon. — The stipes in this form are very 

 Fig. ^.-i)i.iu,,ra,tus separatus, Elles. ^^.^^.^,q^^. ^ud rigid ; thosc of the first Order are longer 



k\ than those of other species of the same genus. 



7% Each of the stipes of the first order is fully o mm. 



;'/ in length, and thus what the earlier authors would 



^',4- liave regarded as the " funicle " is about 6 mm. long. 



yl The stipes of the second order are about 3 mm. in 



[^2 length or rather less, and the pairs of this order in- 



I" elude an angle of about 105°, while the pairs of stipes 



^''^EnS^^ueSprxJfi^^^^^^^^ of the third Order include an angle of about 70°. 



The thecge are very indifferently preserved, and 

 details are obscure. 



Affinities. — This species is easily recognised by its small width and its long stipes 

 of the first order, Avhich serve to distinguish it from D. octohi'achiatus, the only other 

 species at present recognised. 



Horizon and Locality. — Arenig, Middle Skiddaw Slates. 

 Lake District : Outerside. 



Associates, etc. — Only two complete specimens of D. separatus arc known, both 

 of which are in the Woodwardian Museum. The species occurs associated with 

 fragments of other Dichograptida? in the IMiddle Skiddaw Slates of Outerside. 



Genus LOGANOGRAPTUS, TTat/. 



1868. Loganograplus, Hall, " Introduction to Stiuly of Graptolitidao," N. Y. State Cab. Nat. Hist., 

 20th Ann. Eep., p. 226. 



]\ili/j)(ir;/ typically bilaterally symmetrical, consisting of sixteen main mn'serial 

 stipes, which ai'e produced by I'cpcatcd dichotoinous division through 

 Didijmo(jrapl'Us, Tclnujrajitiix, and I )ii-li(»jr(ij)las stages. 



Thccie simple, overlap[)ing tubes. 



