DICELLOGRAPTUS. 



1G3 



very evident, and so pronounced as to cause a conspicuous protuberance of the 

 apertural region in the form of a knob projecting from the general ventral margin 

 of each theca. At least five thecas near the proximal end are distinctly spinose ; 

 upon the remaining thecae, however, spines appear to be absent. 



Affinities. — D. caduceus presents a superficial resemblance to I), intortus, but 

 from this and all other species the peculiar shape of the polypary and the 

 characters of the thecae easily distinguish it. 



Horizon and Localities. — Lower Hartfell Shales {Dicranog. Glingani zone). 



8. Scotland. — Dobb's Linn ; Hartfell Spa, etc. 



Associates, etc. — D. caduceus occurs in some abundance in a single band of the 

 Lower Hartfell Shales (Dicranog. Glingani zone) of Dobb's Linn and elsewhere, 

 where it is found in association with Dicellog. Forchammeri and various Dvplograpti. 

 There are good specimens in the Sedgwick Museum and in Lapworth's collection. 



to the Genus Dicellograptus. 



D. pumilus. 



Widely di 

 vergent, 



slightly 



flexed. 



axil 

 square. 



25—3 mi 



10—7 



Gently 

 curved, 

 narrowing 

 apertu- 

 rally. 



Trian- 

 gular, 

 width oi 

 stipe. 



j rounded. 



■4 mm. - 8 mm. 

 15 mm. I 13 mm. 

 10-8 I 12—10 



axillary 

 ingle 60°. 



Curved, 



introverted 



and intro- 



torted. 



Pouch- 

 shaped, 



D. Forcham- 

 meri, 





D. Morrid. 



D. mofa- 



1 >. i Ic'itnit, 



Widely di- 

 vergent, 



var. 



JliJIKKUS. 









■- 



Slightly 

 divergent, 



Sub- 

 parallel, 

 then 



Divergent. 



- 



Hexed. 



slightly 

 curved, 



divergent, 



graceful 

 . double 

 curvature. 



axil 







axil 











square. 





rounded. 







l - 2 mm. 



1 nun. 



13 mm. 



1 5 mm. 



■8—1 mm. 



1*5 mm. 



- 



15 mm. 



1 mm. 



2 — 3 mm. 



10—8 



- 



12—9 



11-9 



10—8 







Strongly 

 curved. 















Deep, 



_ 



_ 



', s width 



J width 



j width of 







of stipe. 



of stipe. 



stipe. 



straight. 



Crossing 

 twice to 

 form an 8. 



1 mm. 

 15 mm. 

 11—12 



Very 

 strongly 

 curved. 



strongly 

 intro- 

 verted and 

 intro- 

 torted. 



', width 

 of stipe. 



