502 



BRITISH GRAPTOLITES. 











Specific Characters of Forms belong- 







GROUP V. 





31. lobiferm. 



3r. runeinatut. 





M. Beeki. 



JJ/. exiguus. 



31. nodifer. 



3/. criipu: 









var. pertinai. 













Character of polypary . 



Slender, 

 long, flexed 



Slender, 

 somewhat 



Stiffer and 

 straighter 



Long, 

 arcuate, or 



Short, 

 slender, fish- 



Like M. 



exiguus 



Like note of 

 interrogation 







or straight 



flexed in 

 proximal 

 portion 





with irre- 

 gular flexure 

 in proximal 

 portion 



hook form 





in form 





Maximum width .... 



2 mm. 



1-5 mm. 



— 



1 mm. 



■5 mm. 



•9 mm. 



— 1 mm. 





Length of sicula .... 



1-2 mm. 



1 mm. 



— 



— 



■9 mm. 



•9 mm. 



1 mm. 





Characters of thecse : 

















* 



1. No. in 10 mm 



10—7 



11—8 



10 



10 



14—12 



12—10 



7-9 





2. Overlap 



Insignificant 



Insignificant 



1 

 7 



— 



Insignificant 



— 



— 





3. Proportion of apertiiral region 

 to width of polypary 



3 



* 



i 



— 



Like M. 

 lobiferus 



i 



A with 

 double fold 



3 2 



* 3 





4. Proportion of lobe to thecal 

 length 



3 



4 



i 



• — 



— 



i 



4 



T 



4 2 











GROUP 



VI.— A (BIFORM). 











M. convoliiiui. 



M. decipiens. 



M. urceolut. 



M. triangulaius. 





31. raifz- 

 hainieniii. 



ii. 



denticulafu». 



3f. tpiralii. 













var. major. 









Character of polypary 



Flat spiral 



Small, 



irregular, 



plane spiral 



Loose, 



helicoid 



spiral 



Small, circi- 

 nate, with 

 recurved 

 l^roximal 

 portion 



Curvature 

 broader 



Arcuate, 



with broadly 



circinate 



proximal 



portion 



Small, 

 arcuate, 



broadly 

 reciirved 

 proximal 



portion 



Eobust, 



irregular 



spiral 





Maximum width 



3 mm. 



2 mm. 



2 min. 



2 mm. 



— 



1"5 mm. 



13 mm. 



3 mm. 





Length of sicula 



— 



Short 



— 



•9 mm. 



15 mm. 



1 mm. 



1 mm. 



— 





Characters of thecoe : 

 1. No. in 10 mm. . 



10—7 



10—8 



11—12 



10—8 



12—7 



12—9 



8-9 



8—9 





2. Proportion of " barb " to 

 thecal length 



1 



\ 



Merest 

 fraction 



1 

 4 



1 



4 



i-4 



Proximal 

 like M. tri- 

 angulaius, 

 distal like 



M. 

 communis 



X 





3. Proportion of theca isolate 

 (mature) 



f 



7 



3 



i 



i 



i 



— 



i-i 





